I've seen a few of the Thai DTA's as well (but not the Thai-Australian DTA). As @oldcpu says above, what I've also noticed in common is they refer to a former 'government' worker's occupational pension that would not be taxed in Thailand, but all other pensions, like the ones most people get in their old age from their governments, no matter where they worked - let's call it the State Pension - is taxable here. If I had to guess at why that's so common, it's probably because it allows the source country to keep the tax directly - so most countries would want that. Other Aussies can probably best answer this case.