CA may well be an exception.
Due to a 2019 court ruling (known as the Bindley decision), the income of sole proprietors providing services to clients in California may indeed be subject to California taxation, even if the service provider is a non-resident of CA and never performed any work in CA.
You can read the details here: https://www.coblentzlaw.com/california-office-of-tax-appeals-gives-precedential-authority-to-bindley...
Therefore if you receive a 1099-MISC from a California-based client, the State of California may be looking for you to file a non-resident CA tax return for that income.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
