Anonymous participant “ I literally said I can apply on my own “ - you literally asked for agents to apply for you. That was the point of your post in your first sentence. 
“ A huge portion of nomads in Thailand, with very little to no real intention of actively attending classes “ - wrong. Where is your data?
“ let’s not pretend this is a moral high ground situation “ - You taking advantage of the goodwill of a host country who are trying to promote aspects of their culture, is quite literally a moral high ground situation. In fact, most of life is a moral high ground situation, unless you’re a selfish sociopath.
Anonymous participant yes, they check if you are actually doing what you’re supposed to be doing. If it’s language, then you better be able to answer their questions in Thai after a few months.
They have other ways of checking. If you are fraudulent and simply doing a “class” for a visa and not attending, it’s likely a ban from the country…
Asked every day. Agents are a total waste of time and money for DTV. You have to assemble all the docs yourself to give to the agent, by which time you might as well just upload them.
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