I agree with that. It's a good model for settled stellar regions, where interstellar trade is a routine occurrence.

In less settled regions, a different model operates. I've been reading the "Suns of Gold" supplement for Stars Without Number, the trading system of which assumes that almost all worlds are self-sufficient in basic industries, leaving interstellar trade restricted to high-value goods and services. There's a sidebar in among those pages that I found particularly inspirational:

"It’s a Dirty Job

As you might guess from this chapter, a scrupulously honest and aboveboard far trader is not long for the business. Trying to play by every law, regulation, tariff, and fee piled on top of a far trader’s business is a recipe for bankruptcy. To most worlds, far traders are the quintessential dangerous outsiders, the sinister figures of temptation and dark bargaining. The individual good they do for people and the benefit their trade brings to a planet are easy to overlook because the benefits are spread widely, while the threat they pose to existing power structures is very specific.

As a consequence, most far traders respect no planetary law. The dirtside powers are their implicit enemies, the natural opponents of their essential right to trade. They will do whatever they can do to evade the snares and blockades of their business, tell whatever lies are necessary to get their trade through and corrupt, suborn, and befriend every possible official to open the way to their business. If they’re not smuggling, it’s because the numbers don’t add up for it. Those unwilling to do these things rarely last out their first trading trip.

Still, many traders maintain a stubborn core of moral principle, a few basic beliefs that they won’t compromise for any earthly price. An honest deal, a true word of honor, a cargo haul made even in the teeth of an empire’s blockade - these traders are true to themselves because they’re the only ones they can trust. The dirtgrubbers might deserve all manner of deception to ensure the natural right to trade, but these merchants won’t sell out their own principles.

And others, of course, are just unmitigated bastards."

--

Richard Aiken

"Never insult anyone by accident."  Robert A. Heinlein