If you have kids together, the restraining order is going to be very limited due to custody issues. A no contact order would be silly in that case.
No necessarily, the custody issues might be solved. e.g. what if a couple (with kids) break up due to the husband beating the wife and kids. Father gets no custody and there is a restraining order to prevent him contacting them (y'know so he doesn't beat them again).
Not an option for some people. You need savings and cash while hiding. What if you have children, can you just pull them out of school (say), while you hide? How long would you hide for? 5 years?