There are millions of "impenetrable locks" in our society -- things you can do that might give the government less than 100% control over you. You could put your money in crypto where it can never be seized, should crypto be illegal? You could bury your money in a forest where it can never be seized, should shovels be illegal? You can stab somebody with a knife, should knives be illegal? You could fly to a foreign country, should flights be illegal? You could discuss a crime in-person not over the internet, should private conversations be illegal?
The fact is, unless you want a totalitarian state, the agreement is that society functions without perfect control by government, and most of us prefer to live in such regimes. In fact, most of us recognize that regimes that want more and more power over the individual usually end up misusing it.
THe easy boogey-monster is child-porn, but that's bull done by a tiny fraction of the population. The real monster is authoritarian governments, which are the majority of governments in the world.