Did you really just say that?
For real?
Hmmm.... Jeremy, I am not sure how to understand your post. Are you expressing an outrage at the notion that Americans are somehow more morally inclined to exploit "dumb" schemes? Or you, perhaps, find it so obviously true that no question was necessary? Judging by Chuck's subsequent reaction, looks like you had the former in mind.
However, all moral outrage aside, I think that OP is onto something here. As a European (living and working in both Eastern and Western parts), now living in the States, I can see the difference in what OP was talking about. Not that I would ascribe it to any particular or inherent moral flaw of Americans (nor I think OP had that in mind).
The wide-spread practice of free offers, 100% money-back guarantees, no-questions-asked product return policies, etc., is having its consequences. Some of which are unforeseen, some are calculated. Where I was born and raised, such practices were simply unimaginable. Products could be returned only if seriously defective, and even then with a lot of hassle. As I was moving west, I was gradually exposed to more and more of the current marketing and financial practices. There is no doubt in my mind that the U.S. is the most advanced market with such practices. I've seen people, even generally considered well-off, wearing clothes with price tags still attached (so that they can return them at the end of a 15 or 30-day return period).
Some people are intentionally abusing the system. Some are seeing it as yet another marketing ploy designed to nudge you to buy easier, with foreseeable abuses already built into the price. In the latter case, they might see it a less morally reprehensible to (ab)use the offer. Some others might also see certain offers as marketing give-aways (where a certain percentage of non-paying customers is simply seen as a cost of doing business). And, once again, I am not saying Americans are more inherently susceptible to this relaxation of moral principles. Just that they are more exposed to the temptation. As those practices spread even more to the rest of the world, I am sure human nature will react the same in due time.
There is another aspect in play here as well. In any good book on the "art and science" of influencing (e.g., my favorite, by
Cialdini), you will find a reciprocity principle, i.e., where a little favor to you (say a free gift) is subconsciously provoking you to reciprocate and return the favor (by buying or donating). Before moving to the States, I have never had labels with my address preprinted on it sent to me for "free". Nor calendars, notecards, X-mass cards, etc. I even once got a coffee mug with my name printed on it. While initially you react subconsciously to such acts of "kindness" and readily reciprocate, you soon realize the marketing ploy nature of it and become cynical about it. As a result, I no longer feel obliged to donate or buy just because someone sent me free address labels, for instance.
Another reciprocity example: it has been proven by experiment that, for instance, street performers who offer you something (say those animal-shaped balloons) make more money if they have a policy "free, but tips gladly accepted" than if they set a price. Some people will, of course, take the free balloon and walk away, but overall, the performer will ultimately make more money that way.
To the OP: I am not sure why it happen that way. Perhaps the customer has been on a long trip and will ultimately pay (although your reference to his "recent" postings here indicate you do not think that is the case). Perhaps he sees your offer as one of those I described above (i.e., as marketing give-aways, where a certain percentage of non-paying customers is simply seen as a cost of doing business).
As a suggestion, you might want to switch your practice of try-before-you-buy to a money-back guarantee. That way, the burden of extra step is on the potential cheater.