Unfortunately you are mistaken, in the state of California, if you are detailing cars on a mobile basis, you need a California car washing and polishing registration which is a licence you need on top of tax, business and insurance licencing. People here get busted all the time here for not having one and its a $10,000 fine, I know a reputable detailer who has gotten one of these.
And here is the proof:
How to obtain a car washing & polishing registration certificate
And it has a lot of requirements and expensive insurance and bonds are required in order to get it. So I get all of this and people who are not legit undercut me because they dont have to pay for any of this which annoys me. Makes me want to move to another state and start up there.