Now that I'm actually awake, and looking at the original question... "Who the hell travels with a low passage in the Classic Traveller universe?"
We know, roughly, the average per capita income. Ok, we have two incompatible sources, but we can bracket from them.
Striker's rate is a good baseline.
Running some numbers based upon imperial worlds in the Marches - a bad baseline, but a baseline none the less - of Cr 14954 per person.
So KCr15 per person. (This is slewed pretty badly, though, but the high-pop high-TL correlation. Keeping in mind that 90% of the population lives on 8.3% of the worlds.) This gives, using standard imperial 4-week months, Cr1150/mo; using modern 30.43 day months, Cr1246/mo.
This puts a round trip mid passage ticket higher than 1 year's income for the average man. Directly comparable to a 14-day ocean cruise line passage. Which said cruise is, for the average guy, is a once-in-a-lifetime trip, and quite possibly a "never go anywhere"... And High passage is 25% more cost, and so even less feasible for the average guy, at 1.34 years vs 1.07.
The Low passage is just under 2 months salary for the same trip... 1.7 months salary. The average guy might be able to swing this several times in a career. He's unlikely to do so, but he might. So, let's figure that 0.1% of people actually want to get off world (which matches some poll I saw over 10 years ago).
Let's also assume a fairly normal wealth distribution for western nations (a major stretch) - I'll draw from the UK, because the data is available easily, and average the various indicator percentiles' income point as a fraction of mean income over the data range to hand to determine that... we get the following breakpoints:
Percentile | 1% | 5% | 10% | 25% | 50% | 75% | 90% | 95% | 99% |
Cr/year | Cr3394 | Cr4071 | Cr4802 | Cr6716 | Cr10426 | Cr16422 | Cr24623 | Cr33459 | Cr76089 |
Fraction of Mean | 23.252% | 27.892% | 32.902% | 46.016% | 71.429% | 112.509% | 168.7% | 229.235% | 521.3% |
Cr/month | Cr261 | Cr313 | Cr369 | Cr517 | Cr802 | Cr1263 | Cr1894 | Cr2574 | Cr5853 |
This gives us Joe Normal actually making KCr10.4. Which pushes a high passage to 2 years income - that's also, not surprisingly, the low-end price range for buying an RV. The kind of thing you do once, and pay for for 10 years.
For the bottom 25%, even low passage is a major expense - 4-8 months income.
So, who travels Low?
Looking at the generated extrapolations...
The middle income class retiree who wants to get off world. He scrimps and saves, and freezes himself for shipment.
The lower income class escaping a bad situation. Probably one way.
The terminally wanderlustful who lack the skills to hitchhike (working passage) - think like the guys who get out of the military, and then go on walkabout for a decade.