Let's address each point in turn...
Handled through the courts and the extensions thereof. Which country you open the suit in will depend on countries involved and existing trade agreements.
This is a free market. South east asian freelancers are often paid less than those in the west for 3 main reasons.
- Language barrier
It exists. Sometimes it is just quirks and idioms, other times it is more
- Preference for local developers
Cultural preferences, available times, etc
- Work style
Having worked with software devs from all over the world, there is a definite cultural difference in approach to development work between the west and SE Asia.
This is more of an observation than my own preference (I have previously been asked if I can recommend people based on the criteria of being British).
Again, free market. Put better conditions into the contract. As for discrimination, I have not encountered this and am unable to comment.
Ultimately, the contract between the freelancer and the client should be written in such a way as to protect both parties' interests fairly. If you, as a freelancer, sign a contract that crucifies you, the only person at fault is you.