Termites are very common in wood framed homes in the Southern California areas. The dry wood type (ones that fly) more so than the subterranean I believe. I have been told they swarm 2 times a year looking for new places to live (and infest). When a pest company inspects for termites I doubt if there is a company that will find them all due to the inaccessible areas in a house. I believe the inspection report states something about that.
The subterranean termites are not as common in my area but I have come across them a few times. They can be much harder to get rid of and are harder to treat and I would recommend follow up inspections. I believe in the East coast the fear is related to the subterranean type more.
The point I am trying to state is that I do not believe you will be able to find a wood framed house in Southern California totally free of termites.
If you do not want this house because of termites then make sure you realize the next house will likely have termites too. The tenting of a house will kill the dry wood termites and other bugs, spiders, etc, even the ones in inaccessible areas. Regular maintenance and general care of the exposed wood on a home will definitely reduce the risk of wood pests like termites but I don't know if you can eliminate it completely for an extended time period.
If you do not want to continue with the purchase for this or any other reason and if you removed ALL your contingencies you have money at risk. Review your contract, it addresses what the amount could possibly be based on certain factors.
You really need to get your Realtor involved and maybe their broker too. There are many variables here and a lot depends on the sellers.
Brian Wilson, Realtor