It really depends what sorts of compiler bugs you're referring to. I think you're thinking of codegen bugs, which are indeed rare. But on the front-end/parsing side for something like C++, it's really not uncommon to encounter buggy compiler behavior. This isn't an indictment of their developers though - the spec is just super complicated and confusing with weird corner cases and ambiguities.
Can confirm that I routinely run into situations where I think the C++ compiler should be able to _nearly_ trivially infer the types code I'm writing, but for some reason or another, it can't.
I have no idea if these situations are due to the spec, bugs, or a mixture of both, but they do happen, and pretty frequently at that.
