This has no bearing whatsoever on personal income. Wages are sourced exclusively based on location of the employee regardless of location of benefit. a marriage counselor advising a CA couple from NY is 100% NY source, and if he's in CA advising a NY couple, it's 100% CA source.
If a CA business pays 90% of it's revenue as wages out of state, it's CA corp tax will only apply to the 10% profit, and if it pays 100% in wage it will have no CA tax. It may be an invitation for an audit though.
Netflix will have to pay corporate income on the portion of it's profits that are resulting from sales to viewers in California, but when it pays wages to it's employees, if they performed the worked out of state they are not taxed by California even though the income was CA source for Netflix purposes.
But of course, the easiest way to determine these complex definitions is:
You, and most people typically misunderstood and get this part wrong.
a marriage counselor advising a CA couple from NY is 100% CA source. You need to file CA and NY, then get the tax credit paid in CA back to NY.
However, if the CA couple flew to NY and the marriage counselor can prove that work were given only when the CA couple is in NY (can consider them as NY client) then it is 0% CA and 100% NY.
That is why timesheets or signin log is very important but nobody cares.
Now will the state really care this much? Yes only if you get audited. Most likely you will get away with this mistake. Timesheets will be your best or worst friend depending on how you treat it.
TurboTax might get this wrong too if you still believe it is NY income not CA. This is the only drawback of pushing interpretations to the edge. Tax software can't really make a judgement call for you.
Same goes with Netflix. It is almost impossible to track a typical Netflix employee of their work contribution, therefore the employee residency kicks in. However, if you are a Netflix employee that does nothing else but in CA, i.e. sales (marketing) team focus ONLY in CA even if you are based in TX, you are taxed by CA.
Again will the state really care this much? Yes only if you get audited. Your best excuse is Netflix issue you a W-2 state incorrectly. (but doesn't make you right, maybe less penalty)
You can disagree as much as you want. I'm just telling you the what the rules says not how the rule is enforced or what is commonly done in general.