everyone has got the same rights (and obligations), and someone like Ryan complaining that Philippine teachers take his job is either racism, pure greed and meanness, or both

Indeed! And with that comes obeying the contract of your primary job, the one that sponsors your Z visa, and clearly states it is not allowed to take on outside work.

Teachers from the phils seem to ignore this and think it is their right to pocket as much as they can...without paying any tax, nor do they think it is immoral.

If everyone has the same obligations, then that should mean following the contract dilligently and honestly, and not evading tax, right?