Nor do I -- but I'm pretty sure that those shortcuts are pretty much the only good reason for caring much about having names that resemble CAR/CDR in the way FS

Nor do I -- but I'm pretty sure that those shortcuts are pretty much the only good reason for caring much about having names that resemble CAR/CDR in the way FST/RST do. (For any other purpose, I think FIRST/REST are obviously better than FST/RST.)