You also would like to expect that if the law is unjust, it can't manage to make too much harm while getting repealed.

And repeals can take a long time. If people would easy organize for things like repeal a law or a government which suddenly become despotic according to majority opinion, we'd live in a different world. What we're trying to make here, banning face recognition, is to make mistakes in laws less costly - sometimes way less costly.