But his Singapore Tax Residency may take precedence over Thai Tax Residency. The DTA provides the mechanism to decide which prevails. It's more to do with residency rather than where tax is paid. Read the DTA. The same applies in Australia. I have dual tax residency but am only required to pay tax in Australia, and I am not required to submit a tax return in Thailand. His situation might be the same, I'm not saying it is, but it's certainly worth exploring
If you are in Thailand on a DTV, you are effectively a tourist, in which case I would guess you have a permanent home in Singapore. If this is the case, your Double Tax Agreement makes you solely a tax resident of Singapore, so you are not required to submit a tax return in Thailand. The changes to Thai taxation this year are not intended to tax tourists. I would suggest you apply for a Certificate Of Tax Residency in Singapore which effectively rules you out of paying tax in Thailand
It's not scaremongering. It's simply making the OP aware of what might happen. There seems to be a bit of a surge in denials and/or warnings since the exempt was pushed up to 60 days
The difference is (and this is known to border immigration officers) is one you have paid for, the other is free. It appears that immigration officers do not like those entering frequently on free entries