You’re making false equivalences, and ignoring all of the fundamental differences between the technologies. The materials involved are different, the chain reactions are different, the kinds of radiation and half lives are different, the way you build the cores are different (and are still being worked on for fusion).

The entire reason why people are working on fusion IS the fact that it’s much much safer due to all of the key differences. That doesn’t mean there aren’t lessons from fission to transfer, just as lessons from ICE cars have gone to EVs.