So even if FMT were FDA approved, it would be hard to find donors in America.
Yet, even you would realize that "hard to find" is not equivalent to "impossible."
When aiming to produce a product for general consumption, you're either fulfilling an existing demand or you're creating demand. "What do people want?" They want everything. When people want everything, that means they need to be hooked in order for them to even notice your product. These companies are subject to the same ignorant, incompetent and lazy audiences as we are, yet they get people to buy their products anyway.
People walk into the doctor's office and their "numbers" return "normal" and "unremarkable" all the time. Therefrom, the doctor claims their health is perfect. I'm sure plenty of these people went on to die of heart disease and other ticking time-bombs. Tests are for ruling stuff out, not for asserting health. Many doctors have yet to come to this realization.
It is not difficult to simply look at a person and tell whether they'd be a potential stool donor. From then on you would entertain deeper forms of investigation. The issue is that the longer we wait, the less likely there'll be. Even Japan, which is rated as one of the top countries in having a good microbiome, have been slowly implementing Western cultural practices. Even so, I would still argue that there will always be someone, somewhere, that has a fairly good understanding of health and nutrition as a result of their own experiments that does not entertain poor lifestyles, which would be suitable as a stool donor. Even if they happen to be on the same level as hippies.
However, this is not to say that it is impossible to bring someone with fair health into good health, that they might have a desirable microbiome. Technically speaking, just finding even one ideal donor would be sufficient to improve everyone else. In the end, if no one does anything, then "hard to find" would be no different than "impossible."
You could argue that South Park made it go viral, and that had very little impact. Few people have the motivation to make FMT go viral because they can't make money off of it. They'd also likely need a super-donor. Hoping that some random person will make FMT go viral and that will solve all of our problems seems like a fantasy.
Considering your own efforts, it is strange that you would echo the claim that you can't make money off of FMTs. Even if the world we seek is nothing but a fantasy, I'm sure that wouldn't stop you from chasing after it anyway.