The letter of the law in a lot of places can be even worse than that. [1] There's been federal legislation proposed but AFAIK, nothing has been passed. A lot of states theoretically require you to file a tax return even if you only travel there for a day. Of course, I'd be shocked if pretty much anyone complied with that for sometimes travel. But it means lots of people are basically committing tax fraud; many/most probably don't even know they are.
I did on internship in Texas when living in California. I had to pay California state income tax on what I earned there. Luckily Texas has no state income tax or I would have been paying in both states.
[1] https://www.pewtrusts.org/en/research-and-analysis/blogs/sta...