GURPS rules in general or the rules introduced by FT? I'd agree with you if the first, disagree with you if the second. (Well, the rules that I routinely use, which is admittedly only some of them, are reasonably easy).
GTFT in specific. I find core GURPS rules reasonably easily usable. (no longer appreciating the misplaced details is a different matter.)
What's the difference between 2) and 5)?
2 is using the wrong basis for trade; high speed of delivery is part of the model, a part that they may have undervalued
5 is ignoring the evidence that a gravity freight model is dependent upon fast communications. A part that they considered but probably undervalued.
That's interesting. Could you elucidate?
SImply put, Jim, Blue, and Chris have all stated they don't believe speculation significantly different from freight.
They are, respectfully, woefully ignorant of the historical modes of shipping before the telegraph; the majority of materials shipped by sea were high value consumer goods, and almost no staples of life. Food would rot in the trans-atlantic, trans pacific, and asia-europe trade flows; it did not go. Textiles and spices flow more than most other things, because their inherent rarity of production means speculation will almost always provide a return on investment.
Only one spice is essential for life; salt. Salt has been traded on speculation, almost as specie currency, for all of history. Where you can collect salt easily, you can buy whatever you need... excepting fresh foods from far away.
We don't see lots of food shipping to England from the US; their breadbaskets were closer... france, italy, and the middle east. The Potato Blight: it was easier to sent starving people to the food than to buy and ship food to the people. The guys shipping food on spec (a few irish skippers) were able to make an ROI, but the food they shipped wasn't enough to prevent famine. By the time the captains abroad were able to buy food on spec, the famine was claiming lives in abundance.
All of which leads to the conclusion that the gravity model used is invalid if the communications are too slow.
Now, we are talking travel times for goods on the order of several weeks.
Also, keep in mind: England was able to feed all of Britain up through the late 19th C; once communications took over, she began to import US food as a demand item, that is, as freight: "I'll pay you to carry the 5000T of grain I've bought by wire so I can feed my cattle." Lo, and behold, the UK population density climbs rapidly from that point. Prior to that point, all societies had localized farming simply to survive, because without reliable communications food does not travel far. And farming limits population density.
Roman trade in the med, likewise: fruits travel as luxury goods, seldom ordered, almost always bought and resold by the merchant, from north africa to Italia; speculation. It's still speculation when the merchant has a standing request; he can't be certain the requestor will still pay when he gets the goods back. What fruits didn't get sold was eaten, used as crew rewards, etc, so fruit moves relatively well by comparison to grain. That which moved by orders was gold, salt, art, wines, olives, and dates... standing orders by virtue of taxation. Rather than the pull of need, the push of tribute moving those items. Rome and Byzantium did ship in food... from only a few days away. But that flow of food on steady demand does show a very localized pattern.
GTFT accurately models a demand-filling mode, but given the slow speed of communications and travels, I don't think they accounted for distance well enough, nor for the difference in what moves nor how it moves. One can only fill a demand either by guesswork or by sure knowledge; at 1J, we see a 2 week lag, which is right on the edge of the demand mode historically. Past that, little seems to move by demand. at 4 weeks (minimum possible 2J time), the majority of trade was owned by the merchant. At 6 weeks or more, 3J minimum time, as with the transatlantic trade of 1700-1850, almost all passengers are government agents or colonists on one-way, and almost all goods are purchased by someone aboard for sale at the far end.
Plus, the presumption that flows will replicate those by rapid mode...
GTFT assumes a direct continuing growth of trade across the interplanetary boundary; however, one should note that in ancient societies, the flow of food to large centers was a function of taxation, not trade, and the outliers didn't feed the center, the fed the middliers, who fed the central, simply due to rats and rot. Londinium was not fed by Cornish food, but by the outlying areas immediately surrounding Londinium, and only so far as the neighboring counties, really. It did, however, buy wool, wood, and other durables. And it likewise sold weapons, wagons, and beer widely.
I don't see that, either. As a location's population crosses a threshold point, without rapid communications with outside, it reverses the specialization trend of the middling sized populations, resulting in the mixed industry and commerce models of 1700's London, NY, Atlanta, Paris... these places, as they grew, once again started to diversify, and reduce their need for outside goods. On an interstellar scale, again, the communications lag is significant, and the ability to inform for demand reduced; local despecialization is the obvious and only logical recourse. As you get bigger, you need to get less trade in essentials because you can't know in time to find alternates before crucial failures.
In modern trade, gravity based:
Joe needs widgets for his factory to run.
Joe looks for widget suppliers, sends them a RFB.
Joe picks the bid he wants, orders and wires the money.
The supplier packs and ships those goods.
In pre-telegraph
Joe needs widgets.
Joe has to pick one of several modes
1) hire agent to go get widgets
2) order widgets well in advance
3) find a local alternative to widgets
4) buy what few widgets come in
In case 1, joe has to send a man to a specific widget source. He can't compare as well. He can, however, mitigate by sending money for 2/3rds of his expected demand each with 2 agents to different sources, and orders to wheedle it down as best as possible. Or 1/2 to each of 3, or 1/4 to each of 5. Enough so that no one supplier can cripple the factory by jacking widgets too high.
Case 2, he's now ordering not for current need, but projected need; he's speculating and taking far more of the risk upon himself, even than 1. If travel minimum is 1 week, he's got to order 3 weeks in advance (to allow for loading and shipping); at 3 weeks travel, 7 weeks in advance.
Case 3 might not be possible; long term, Joe's better off building a local widget factory in many (but not always most) cases.
Case 4 only works if widgets are flowing goods, or merchants know Joe needs widgets.
In any case, as the number of widget needing locals grows, the benefits of someone locally making widgets climbs, since "time is money"... the benefit of knowable local orders makes imports riskier; the local producer can be more responsive to fluctuations of need, and can deliver faster and with lower risks of loss.
