The OS can be smart enough to load identical libraries once. But it requires them to be the same file. This can be achieved with Docker image layers and sharing the same base layer between images. It could also be achieved with content-addressable store that deduplicated files across different images. This would be helped by container packaging system that used the same files across images.

Page sharing can also depend on the storage driver; overlayfs support page cache sharing and brtfs does not.