We should ban the ownership of non-trivial safes for the same reason then. We should also prevent people from writing things in non-approved languages, in case in makes the understanding of things more difficult when a warrant is served.
Hell, if I just hide my information in a stack of a million other paper files, that would be enough to thwart all but the most determined investigator from accessing it without my cooperation.
A long time ago I worked in a guarded military vault with lots of safes - I've never seen one that would take more than an hour or two to break into. The idea is to slow an attacker down long enough that they can be detected and security can get on the scene to deal with them.
None of your examples would prevent an investigator from finding evidence, only delay them. Strong encryption enabled by default could slow down an investigation to the point where it would go on past the heat death of the universe.
Hell, if I just hide my information in a stack of a million other paper files, that would be enough to thwart all but the most determined investigator from accessing it without my cooperation.