> I don't see a lot of Beatles songs being sampled, because it costs a lot
These are two different things, from a legal and licensing standpoint. My understanding is that sampling (expensive, no set pricing) and covering (set pricing) are distinct. I think that if you cover a song, you agree to credit the original person as writer and pay them an (industry standard) fraction of the royalties. But sampling requires negotiation for usage rights and can get expensive quite quickly. I suspect people are not sampling the Beatles because it would be expensive, but that's a distinct question from that of whether people are covering the Beatles.
I was curious, and it seems Beatles songs are pretty widely covered: https://en.wikipedia.org/wiki/List_of_cover_versions_of_Beat...