• Hopper can access to a locked container
• Locked container can be simply broken

All I do is expose the vanilla logic. If vanilla allows these that is on them.

So what the use of a lock if there is another way to access a container?

It's a deterent, not perfect security. Like real life locks. The idea is you will know if someone is stealing from you because they broke your chest.

Nothing I can do about hoppers, that's really a vanilla bug that it allows that.

OK I see