I doubt the pensioners are upset about some petty tax they will have to pay.
I am not a pensioner, but I am upset that I may be required to file a tax return.
When I arrived to Thailand I signed up to be treated like a mug by doing the following: 1 year extensions, 90 day reports, penalties for failing to register TM30, dual pricing, various scams.
I did not sign up to file a tax return in Thailand, so buh, bye if that is the case.