Pensions are generally attached to employment. I don't know of any pension scheme which is not associated with employment, except state pensions which are associated with residency, citizenship etc. The Australian DTA has no reference to employment, so the Australian age pension would also be exempt from taxation in Thailand
It says "pensions" which is all pensions, except government pensions which are subject to article 21. Sorry to say, you're not the sharpest knife in the kitchen drawer
Many pensioners ARE ok! There's a few (mainly British) who aren't. As has been pointed out US, Australia, NZ, Canada, Germany are all good! That's a lot of pensioners! 👍👍
Report by mail is 100%. You have the EMS number so you can track when it arrives at immigration. I've used for many years, never had a problem. I can't be bothered to hike out to Chaeng Wattana for such a simple task. The TM30 is only a notification online. You can print it as soon as its done. I do that every time
Basically, as far as tax is concerned, only money you actually bring into Thailand becomes a "tax liability". However, if you have already paid tax on this in another country you will pay little or no tax in Thailand. If you bring cash, although it should be declared, it's untraceable, and if you bring savings from before 2024 it's totally exempt tax