For college admissions, the admissions offices aren't stupid. They generally don't look at "GPA", but compute it themselves. A small private school might need to worry about how colleges interpret their transcripts. But a system as large as California? Colleges will learn very quickly how to weight grades from different levels of classes. They already need to deal with grades being wildly inconsistent between schools. They also get other signals such as the SAT, which provides a consistent measure independent of class level.