Before I became a manager myself I always wondered why some things aren't being fixed. I had a lot of ideas and I was also vocal about those. That's probably one of the reasons I was promoted.
Since then I have realized the challenges of "fixing everything". There is always something to fix and priorities need to be kept in order. There is always limited time and resources so it's not that easy to fix all the things that are not optimal. It also takes a lot of time to fix things properly. It's often more efficient to just improve things gradually to be able to focus on other things as well.
Fixing things that you think are broken is sometimes also subjective. Somebody else might thing the status quo is working well enough and there is no need to change that. Changing things can cause new kind of issues. People also think differently and have different preferences. An improvement for somebody can be a step back for somebody else.