That’s because package managers are designed to use mirrors. You have to verify a digital signature because the package isn’t necessarily coming from the package maintainer’s repo. Docker pulls come from the registry, not a mirror. There is no such thing as a mirror in docker. The registry is something you decide on, and if you don’t trust it, you shouldn’t use it. If the registry itself is compromised, that’s essentially like the private key of a package manager getting compromised. Same risk. The two biggest registries are Docker Hub and GitHub. If either of them were compromised, it wouldn’t take very long for them to mitigate it. The damage would likely be very small. Oh, they can also mitigate it 100% on their side. With a package manager, your computer will trust a compromised key until the package manager removes it, which may be too late.