I'm assuming you're talking about tourist visas, with that "90 days border hops" (single entry).
Working in Thailand on such tourist visa is illegal. Getting a business visa (and thus work permit) is not easy at all. Foreigners are not allowed to hold majority in a Thai company (just as they are not allowed to own land in Thailand). Thailand is a very xenophobic country, and its laws reflect that.
Working around the visa system illegally is not difficult, and many people do that (incl. IT freelancers). But contrary to the popular image of a "care-free tropical paradise", Thailand is one of the more difficult choices to run business in/from.
Working in Thailand on such tourist visa is illegal. Getting a business visa (and thus work permit) is not easy at all. Foreigners are not allowed to hold majority in a Thai company (just as they are not allowed to own land in Thailand). Thailand is a very xenophobic country, and its laws reflect that.
Working around the visa system illegally is not difficult, and many people do that (incl. IT freelancers). But contrary to the popular image of a "care-free tropical paradise", Thailand is one of the more difficult choices to run business in/from.