As far as the residency test is concerned the Australian and US are very similar, although different terminology is used. However, both are very similar to the OECD model
The DTAs generally are based on the OECD model as they are the overseers of tax evasion and avoidance of double taxation. You'll find most countries follow this model. This is the US DTA relating to residency
Every country has different methods for determining tax residency. It's not a choice. It's a situational process. Everyone is different. Thankfully I retain Australian Tax Residency which due to other conditions (agreed by Thailand) takes sole precedence over Thai Tax Residency
DTAs actually provide the formula for determining tax residency! You need to get this notion out of your head that 180 days in Thailand is the be-and-end-all. It's nothing more than a starting point. DTAs blow it out of the water
I'm one of them. I haven't filed in the 15 years I've been "tax resident" here, and absolutely zero intention to file this year. There won't be any enforcement. Tax assessment here is done on a self-assessment basis.