I have lived in California for the majority of my life, and recently I have observed the traffic patterns in a different state, Colorado. Here is what absolutely gets on my nerves when driving in California.
1. The Traffic
It doesn't matter if you are in a big city or a smaller one. There will be traffic at rush hour, and sometime traffic for no apparent reason. Southern California usually gets all of the attention for bad traffic, but the San Fransisco Bay Area is seriously bad as well. There are jut too many people on the road.
2. The People
That leads me to my next point, people can be such morons. The majority of people are just fine. It's the people who are impatient/ don't know the rules of the road that get on my nerves. Two reoccurring themes are tailgating and merging. Angry drivers who tailgate you are the worst. Looking at you BMW drivers! People also seem to not know how to merge properly. Take turns and it will go much smoothly.
3. The Tourists
I will say up front that I am not a tourist hater. I understand that they support the economy of many cities, and that provides for much of our quality of life. But they need to drive normally. No more driving ten under the speed limit until you find the address you are looking for. That's why Google Maps exists, so you don't get lost and clog up traffic flow. Also, if you are going slow and sight seeing please stay in the right lane. Too many people don't understand. The left lane is for passing and making steady forward progress, which means often times going above the speed limit.
4. The Roads
It seems like there is always construction but nothing much ever gets done. There are still pot holes and cracks in places that get very little rain or snow. They go un-repaired for years. The roads in and out of California can also be incredibly boring. Going from North to South, or out of the state? Good luck. It will be long and straight with boring scenery.
5. In N Out Burger
Ok, Im joking about this one! But I'm kind of serious. In N Out burger is good, but seriously over hyped. It's just another fast food burger, that tastes slightly better than other fast food chains. I do recommend you try it though, if you can get through the traffic and bad roads to get there ;).