It may or may not be true, but it seems like there are more weddings performed by freelance Officiants in California than anywhere else.
To perform a marriage ceremony in California, you must be:
1. Legally ordained, and
2. At least 18 years of age.
It helps if you have some experience in front of an audience, but it’s not a requirement.
Generally, the State of California does not audit Officiant ministerial credentials, and you are not required to register with any agency in the state before performing a ceremony — as long as your ordination is current and active, California doesn’t care.
I have never had anyone from the state or a county in California ask me about my credentials. As long as you fill out the marriage license the way they want it and you return it on time, there’s no problem, but it’s better to be safe than sorry and be legally ordained.