"Draconian law" doesn't mean "an overreaching/unnecessary law" or "a law I don't like", it means "a law backed up by extremely harsh penalties". I'm not advocating for them, but draconian laws would absolutely solve this problem, including trading by proxy. Nobody would risk the death penalty to help a friend or relative trade stocks.

People get the death penalty for white collar crimes in China all the time and it never seems to stop them.