An example for this is the Blender addon ecosystem. Blender moves very fast, breaking API changes every few versions. Now I am not an addon developer myself, but from github issues I follow, changes are fairly often trivial to do.

Yet, someone has to do them. Ideally it is the creator of the addon, sometimes it's the users who do it, when the addon is not maintained anymore (in case of trivial changes).

It kinda works that way, but it also is some kind of gamble for the user. When you see a new addon (and a new addon developer), you can't know if they gonna stick to it or not.

If you have to pay for the addon, it's more likely they maintain it, of course. But also not a guarantee.