1. Options in representation. California is essentially a single-party state. Switzerland has substantially more options in this regard.
2. California is freaking huge, Switzerland is not. Because of this, you have dramatically different interests between different regions in California contrasted with more homogeneous needs in Switzerland.
3. The population of Switzerland is not nearly as diverse as California. They speak several languages there, but overall you have a group of people with very similar cultural and historical values.
4. This point would require a small novel, but in essence California abuses the system to go around the process rather than go through it. You could describe this as the contrast between cooperative governance (Switzerland) and adversarial governance (California).
In short, if we stuck with George Washington's suggestion to lower the maximum size of congressional districts to one representative per 30,000 people, California might be in better shape. It probably would have also been beneficial to listen to Alexander Hamilton when he called parties “the most fatal disease.”