In our district, students can now only take summer school if they've failed. And generally, they can only take core classes or CAHSEE prep classes (I teach in CA; the CAHSEE is our high school exit exam). So, the options are incredibly limited: Algebra, English, Earth Science, etc. I don't even think any level of history is offered.
The sad part is, this has all arisen from budget cuts. When I attended school, I remember taking Health and Driver's Ed during summer school. It worked perfectly for me, because I had no room for them in my regular schedule. Now however, students don't have that option. They have to take Driver's Ed at lunch, leaving their 4th period class early to make it on time. So, they miss out on instruction in that class, plus any activities at lunch. All in an attempt to save money.