As a UK resident holidaying in California, I was confused both as a pedestrian and as a driver.
As a pedestrian I learned to claim the right of way and cross when it seemed safe.
As a driver I was unable to resolve my confusion regarding turning on red light. If there were no vehicles queued behind me I would wait for a green light. I would otherwise typically wait for a sufficient amount of beeping from other vehicles to then assume that turning on a red was what I should be doing.