For the same reason why two countries have any policy difference? Unless something is obviously a good idea for all parties, it will only be enacted after a po

For the same reason why two countries have any policy difference? Unless something is obviously a good idea for all parties, it will only be enacted after a political struggle. The outcomes of political struggles are not deterministic. Often one jurisdiction tries a new policy, others look at it and see problems, but the first jurisdiction never gets around to fixing it.