Why is out of state retailer charging me their states sales tax?

No, that was the law, but the Supreme Court ruling changed that, as I understand it. It no longer matters if the retailer has a presence in the state to which it is shipping. The retailer’s home state can collect the tax on shipments going out of state if it chooses (and what state won’t?).

Yes, the opinion made it clear the SC would look favorably on a state requiring an out of state entity to obtain a license to ship into the state and make collecting and remitting sales tax a requirement of the license. California is one of the states that wen this route, although not all out of state entities follow that law.

FWIW, I am one of the people who pays use tax on out of state purchases where sales tax was not collected. Now that most out of state wineries and retailers and Amazon collect California sales tax, the amount is much smaller than it used to be.

-Al