The Carpenters were great. I grew up on their music. It was years later that I learned that they weren't really a "band" or even a "vocal group" because almost everything you heard on the albums was the two of them, Karen and Richard, multitracked many, many times.
But yeah, Karen was a great drummer. I'm guessing that when they were growing up, Richard played the piano and/or other instruments, so she'd sing and play the drums just so they could work out the songs, and eventually she got pretty damned good at them.