I tried to read the whole text of the bill but I’d probably need to print it to have any chance at understanding it. But states/counties and municipalities directly tax non-residents all the time - I have to pay property and school taxes on property I own in NJ even if I am a resident of NY. If my job is based in NY and I work at home in Connecticut for my own convenience, I will owe income taxes in NY. Even if I never worked a single day in NY.
The issue wouldn’t be taxing non-residents - the issue would be whether this bill would be taxing former California residents on their assets outside of California. That, I’m not sure if California can do - and even if they can do it legally, enforcement will be impossible. I mean sure, California can tax me on my $300 million house in California even if I live in NJ. They can put liens against it and everything. How do they even find out a former California resident owns a $300 million house in NJ six years after leaving CA?
Assuming this passes ( and that's a giant assumption) mostly what will happen is that very rich people will move out of California and take as much of their assets with them as they can.( Sure, it might be hard to sell the $300 million house- but Jay Leno can move his $52 million worth of cars out of California very easily. Bank accounts are easy to move, too). Which means the tax revenues will drop even more than they already have.