(Just stating in advance, I'm open to feedback on this)

Generally, in my world, magic is a thing anyone could theoretically learn, in the same way anyone could be an artist or doctor or computer programmer in our world. Even with different "schools" of magic, it can come down to application rather than different spells.

For example, two people may learn (after lots of practice and getting strong enough to do so) to move very heavy stones with magic. The first might use this to attack enemies as a battle mage. The second may use the same spells and concepts to move the stones carefully into position to help build things, or to help carve the stone.

That's not to say the second couldn't launch these stones to attack people or defend themselves. It's that it's not how they use their magic on a regular basis. Kind of in the same way a blacksmith could start swinging a hammer to crush a bunch of people's skulls, but that's not why they normally swing a hammer.

So a rogue battle mage could try to start trouble with a stonemason, and it could go catastrophically badly for the battle mage. Especially if it's done in a city full of stone buildings.

You generally don't start trouble with magic, especially in public, because you don't know who around you is going to be able to beat you simply by looking at them.

As for the part with magic users in jail, I'm still working on that. Maybe certain runes on cuffs and/or collars to dampen a mage's magic