1) The only difference between a just law and an unjust law is time. I have family members who needed to wear dog tags to drink in certain pubs because of the colour of their skin, and I'm not old. And yet such laws were widely supported (for various reasons) for a long time.
2) lazy governments often apply sweeping blanket bans and fall back to police discretion. Carrying a hammer? Technically illegal in my home country, and the police can stop you. Whether or not they have have reasonable cause to charge you is a different matter. If you look like a tradesman you probably won't be bothered, but if you don't, you're breaking the law.
3) Laws can be mutually contradictory until legally tested and a precedent is set. If you're unlucky, you could be the one who has to test it. Regulations are notorious for this.
I'm not saying that we don't want to enforce laws, because generally we do. But when and how laws are enforced requires nuance. And certainly the idea that always enforcing them is a net good is very, very far from the historical reality.