All of the above. If surgery starts at 7:30 you've got to be in the room and ready to go at 7:30 (not pulling into the parking lot). There are probably patients to see beforhand. Covering multiple hospitals further complicates things. Then, what if your cases or office hours run a little late. Then, there's charting and other stuff to take care of. Maybe you have meetings somewhere in the mix, too. When on call, you may work all day, do some cases at night, and then start the next day like you weren't on call. Repeat. Orthopaedic surgeons work more because there is more work to be done.
Starting at 7:00 am would be really nice. Right now (I'm on our "good" rotation) I start at 6 am every day and operate all day long (until 5 - 7:30 p.m). Clinic is in the a.m. on Tues and Thurs. I take call 7-9 days a month and don't go home the next morning. 3 of those calls are a Fri-Sat-Sun block (which is brutal, but all the other weekends are off). However, I like to operate and treat fractures, so I don't let it get to me. I don't love to work, I love the work.
Attendings make it what they want it to be. If you want/need a lot of money or are establishing your practice - you work a lot. Call ratios depend on the size of the group. Hours are self/$$ dictated.