Government licensing is a surprisingly pervasive way of driving up wages in a profession. In my home state of Maryland, you need a license from the state in order to be a barber.
Lawyers have it especially good for a couple reasons. First, they (and thus their interests) are well-represented in the ranks of people who make laws, so the laws on who gets to practice law are very restrictive. Second, legal services are one of a small handful of things that you can be forced to spend money on. Nobody forces you to buy an iPhone. But getting sued is something that happens against your will, and when it happens you have little choice but to spend money on a lawyer.