There's a question I answered some time ago (about 2 weeks) and now I see there were some edits introduced a week ago by another person to the question and to my answer. Why am I not notified of these edits? I'd like to be because for instance if the question was changed, maybe my answer is no longer valid (I mean it doesn't answer the updated question and I can loose reputation). And if my answer was changed, maybe it doesn't answer the original question, maybe it's changed completely (at least I can't guarantee the opposite). I assume people with great reputation edit posts and answers only slightly and if there are some mistakes that can easily be fixed, but you don't need to have 10 thousands of rep to make edits, so how am I protected from people trolls or people who accidentally made my answer invalid? I feel uncomfortable with such rules and I'd like to be at least notified of changes.
You are automatically notified of substantive changes to a post you wrote. If you're worried about a question you answered getting edited, you can always follow it and you'll be notified of substantive changes (and comments and new answers) too. It would not be a good idea to make this a standard feature; some people have answered thousands of questions. Imagine the number of notifications they would get; most of them are completely irrelevant and that's a lot of noise to wade through. Edits that completely change the meaning of a post are rare and as @Luuklag says in the comments, they're usually caught (because the edit bumps the post, making it visible again for a lot of people browsing the site and/or specific tags) and rolled back.
You can use the Stack Exchange Data Explorer to regularly check for edits on your answers or their questions. Here is a first attempt for that. Please note that SEDE is updated only once a week, on Sunday morning, so this definitely doesn't work as well as real-time notifications.