The merchant campaign is a big part of Traveller canon, but on Terra Y-2499, does anyone want to sail a tramp freighter around the world picking up and selling cargo and transporting passengers?
Obviously with air travel, there's no little need for passenger transport, other than for cruises, which have a purpose all their own separate from transportation, and low bulk high value items and some high bulk items are routinely transported by air.
Is it economically feasible in today's world to run a tramp freighter as a sole proprietor.
Conversely in Traveller universe, what elements make a tramp freighter potentially profitable?
More flexible schedules and routings
More people traveling as passengers
What else?
low labor costs: a free trader can run with only half a dozen crew, no need for permanent ground staff, no sales teams, just the ships crew. people aren't cheap, and few people means fewer headaches with wages, medical issues, family issues, finding experienced applicants, etc. The existence of the Imperial forces as a factory for churning out trained crew is something that shouldn't be overlooked, given the proportion of pilots who learnt to fly in the military (both in traveller and in the Real World)
low maintenance costs: traveller ships are, relative to modern aircraft, effectively magically reliable, having great uptimes, parts are easy to come by and can be fixed pretty easily and cheaply in most places you might go, all of which make operating a free trader more viable.
demand in the market: a deliberate conceit of the setting, true, but critical, nether the less. quite simply, their is a demand for people able to move a dozen or two tons of goods between planets close by on a ad-hoc or semi-ad-hoc basis, and therefore its possible to find just about enough work to make a free trader possible.
Backwaters setting: it's worth reminding people that the viability of free traders in the Spinward Marches is not proof that those free traders could also be viable in, say, Vland or Sylea, or other core sectors with big, well established economies. the Marches are a backwater, with a lot of small, underdeveloped planets, and by extension, a lot of trade routes too small to justify a permanent shipping line, but, again, their is still demand that a free trader and eke out a living on.
implicit trust: a cultural thing, basically the willingness to climb onboard this ship, operated by a company you have no knowledge of, no real way to check up on, and fairly little way to redress grievances with, and just
expect they will actually do what you want them to.
And that is works well enough to be routine.
low time pressures: the timescales of interstellar travel mean that people are willing to wait on a free trader rather than make great efforts to charter a timely arrival of their goods or people. Free traders routinely turn up at a startport unplanned and find at least some goods that are just sat around waiting for a ship to transport them.
supportive regulatory framework: the 3i apparently enacts price controls and other regulatory mechanisms that ensure that free trade (and free traders) are able to operate. free traders are not competing with the megacorps for price, and are not facing being undercut by those corps using economics of scale to force them out of the market.
