Liberty has never been (nor should it be) unfettered. Public intervention of any kind, whether it's jailing murderers, enforcing speed limits, pulling over drunk drivers, or requiring minimum food safety standards in restaurants, represents a perceived "liberty" being infringed upon. Unless a specific right is protected in the Constitution, it's fair game when it comes to public policy.
I think that opinion is complacent... spawned out of modern wealth and qualify of life.
Liberty is incredibly broad.if you're approach to the constitution (which I think many today share) is that you may restrict anything that isn't specifically mentioned then you are missing the whole point. Eventually aspects of life/liberty that you hold important will be restricted by those who share your approach.