1. Idiot lawyers. 2. Idiot clients.
This will be my main complaint 80% of the time. Some lawyers you work with are great. Bad lawyers are awful. They do an awful job for their clients and make my job 10x harder. They don't understand what is important, and when a lawyer doesn't know WTF is important, they fight over everything because they think it helps their client, somehow.
Clients are getting harder and harder to deal with. They want you to do everything, not missing anything, fight for everything, spend a zillion hours explaining everything to them, then complain about the bill.