Specifically for California, some ballot measures are harder to change/repeal than to pass in the first place[1].

I don't think Congress can write bills that are harder to repeal, but I know some states can. There are also states that abuse their own constitutions to accomplish the same thing, for example if a supermajority is required to amend the constitution.

1. https://calmatters.org/politics/post-it/2020/10/california-a...

I agree with that, but still:

- Bill can undo bill

- Ballot measure can undo ballot measure

- Constitutional amendment can undo Constitutional amendment

so we still have proper inverses.