In my experience from my own marriage based and my fathers retirement based non-O in Chiang Mai, retirement based is considerablly easier to do. Marriage based requires a lot more documents, fresh pictures in front of your house, etc and there seems to be more scrutiny.
That said, after your initial 3 months the marriage based extensions require showing minimum 400k baht for just 2 or 3 months vs retirement needing to show 800k for 5 months (2 before 3 after) and 400k the other 7. Additionally, different immigration offices can produce very different experiences so it may vary a lot depending on where you are going.
As I understand it, it depends on the province. For example, Chiang Mai has never wanted to know when we left the province but stayed in Thailand. I've heard that Chiang Rai still wants to know, but am not sure if that has changed recently.
Are you asking if just paying taxes, being one condition, is enough to get a work permit?
I don't know where you copied this from, but my guess would be that "any or most" should be "all or most" and satisfying one condition would not be enough.
I think the assumption is that working here means banking here. Even if that isn't always true, it probably is true in many cases. OA visa, as I understand it, uses banked funds in home country. It would be relatively easy for an expat using that (the first year anyway) to not even have a Thai bank and just do ATM withdrawls for cash or to keep small amouts of money in Thailand at any given time. I'd imagine that OA extensions done inside the country still needed proof of local funding, so the logic starts to fall apart there if that is the case, but perhaps that just wasn't considered.
The person I am asking for has a foreign company that immigration is aware of and so far has not had a problem with. "So far" is the key, though. The goal here is to figure out a way to ensure full compliance. The person has kids in school so wants to ensure there is no reason he can be kicked out at least until the kids finish school.
Are you suggesting to get a foreign business license in Thailand? It seems that in the same decree mentioned, representatives of a foreign bussiness also do not need a work permit. From what I'm reading, a foreign bussiness license looks even harder to obtain, though.