where did you see that about language courses? Without actually applying for the DTV, I could only find this on the Embassy's site ("activities such as...":
As I said. the money spent is probably much greater than the tax, so not significant. Thail people who don't pay tax (and there are lots of them) are not making that contribution, so this whole issue is not really about community responsibilty but the financial aspect. It doesn't matter to a foreigner whether the Thai Govt or Thai Banks are having free use of their money, and tieing it up, they are losing out. To not pay tax on your super in Australia is not beause it is a tax haven but rather because tax has been paid on that money for many years to set up a retirement free of tax. I'm not sure Thailand will charge people tax on that super money in any case.
”And it costs Thailand nothing”...what does it cost Thailand? What you spend is probably considerable (and most likely a lot more than Thailand would gain from tax). It's more than "a few bucks" tied up in the bank while you are here...