Docker's layer-based deduplication mechanism is ineffective or actively harmful IMO. In practice, different images aren't going to share layers even for the same software because images are always going to be built against the latest base image. To make matters worse, many Dockerfiles run `apt-get update` or other equivalent commands, overwriting what's in the base layers and creating tons of wasted space. Nix does a much better job at deduplication with the Nix store.