It doesn't help that container images typically require you to "opt in" to sharing a cache with the host system. Docker even has a special file mount type for it. I find that people on average don't have a lot of interest in making such things work, they see that it's not available right in front of them and shrug and say "oh well" because ultimately it doesn't hurt them much.

Yeah I'd say most people view it as such, until they hit (docker hub) rate limits.