C, C++, Ada, Pascal, Basic, Oberon compilers for embedded market, in many cases, certificed compilers.
Commercial UNIX, mainframe and Windows compilers (VS Community doesn't cover everything) are still a separate product.
Sony, Nintendo, MS SDKs for their game consoles.
HPC compilers, yeah you can try with clang and gcc, but if you are doing top research, then IBM, Intel, CodePlay, PGI compilers is what you want to be using on that hardware, and they cost pennies versus the total hardware cost.
And even in what concerns Apple, I would consider that XCode is somehow included in Apple^s hardware price.
Are you writing general purpose, portable code code? You'd rather not be locked in to a specific vendor's compiler.
Are you working in embedded systems? Your code is probably hardware-specific, at least to some degree. You probably aren't going to switch CPUs very often. You probably are never going to switch CPU families. You also probably are never going to upgrade the compiler, still less switch to a different vendor's compiler. So if you aren't going to do that anyway, you don't worry much about a one-vendor-only compiler or language.
I think it's a similar story in HPC. You're constrained by your hardware. You get the best compiler for that setup. That means it's hard to change compilers? It's even harder to change your hardware, so you didn't add much of a constraint.