My understanding is that RC is relatively expensive in time (especially for atomic RC) but uses a lot less memory than state of the art fast GC. And RC doesn't handle cycles.
Alternatives have existed since the 1960's, predating C's invention, and also after it came to be, the problem has been mainstream adoption of UNIX, and the side effects from that.
As for C, it leaves verifying the safety up to you, it is not easy at all and I would rather spend time on something else using safe languages.