[eru]

> Animals in the wild don't typically die of cancer, so that's probably not much of an adaptation evolutionarily.

There's lots and lots of adaptations that repair damage to DNA and that deal with damaged cells. So there must have been lots of evolutionary pressure to keep them in place and keep them working.

Animals in the wild probably don't typically die of cancer, because those adaptations are in place.

But you are right, that even mammals active during the daytime have not (re)gained that specific photolyase DNA mechanism that their ancestors lost.