I think other states and provinces may be less strict about this than California. A couple years ago, I took a rental Chevy Malibu - FWD, all-season tires (not snow tires, let alone studded), no-chains - from Reno over to South Tahoe on US 50. It just snowed, the road was totally snow-covered, and there was a checkpoint just outside Carlson City. The NV trooper looked at the tires and let me get on. It was quite treacherous, but once a coach with chains passed me, I just followed it all the way to Tahoe, as it basically ploughed the road for me.

Another time over Colquihalla Highway between Vancouver and Kamloops, British Columbia. Totally snow covered, all-season tires, no-chains. No checkpoint, no nothing. Just electronic signs that say something like "powdery surface, chains recommended" over the 3 mountain passes. Fortunately the car is fully loaded, so pretty good traction. But a 3-hour trip became 5 hours.