California requires non-residents to file & pay income tax for any days worked in the state, regardless of where you live or typically work:
https://law.justia.com/cases/california/court-of-appeal/3d/2...
Sometimes the tax is fine-grained enough to be certain blocks, not just within state or city limits. For example, Portland, Oregon has an income tax (with mandatory employer withholding) for employees working in the downtown district, to fund public transit:
And now it's much more clearer why there is a tax software cartel in the US. If an accountant can barely remember that, an ordinary people would definitely not get this.
At one of my prior firms, pre-pandemic, they fired a remote worker because she moved from one state to another. We thought this was insane because she was one of our best employees and the workflow wouldn't change since she was already remote. The company's logic was that they didn't have any employees in her new state, and they didn't want to take on the additional tax, legal and administrative burden and risks of expanding into that new state.
Employer taxes on the other hand.... who knows?! There very well might be local ordinances that cities levy on employers based of the number of employees or some such thing. Maybe, I have no idea - but the point is: income taxes no, employer taxes, maybe. Would be interested if anyone else knows more?
Edit: City taxes are the reason that "The Strip" in Las Vegas is technically not in Las Vegas. What we think of as Vegas is really in "unincorporated Clark county". I'm sure employees all pay the same State and Federal income tax, but the business don't pay city taxes. I don't know how much that's based off their business location vs. their employees location.
It's really not that uncommon. There are also special districts for things like sewer or water service which can also levy income tax.