Another one that most people overlook in that category are "affirmative action" quotas. They're always sold as "temporary" for the brief time it'll take for their effects to manifest and fix stuff. But alas, in the majority of cases, they are never repealed or "finalized".

One way of interpreting that is that it's easy to sell an unpalatable something as a temporary thing because it sounds "corrective" rather than a final decision.