So when a company chooses the more complicated route to minimal compliance, that's strong evidence that the regulation in question is effective at reducing their illicit gains and would be effective elsewhere.
1. that it may be cost effective just to do everywhere
2. that federal legislators will take note that it is popular
A lot of new laws in the US gain popularity at the state level before becoming national law.
[0] https://taxfoundation.org/state-sales-tax-jurisdictions-in-t...
It's a fairly populous state at over 4% of the US total, I can't imagine national companies nixing PA.
Any online store dealing with gun or gun-adjacent stuff already has been dealing with variations of these for years; knives that are illegal in certain areas, etc.
Home Depot has to block shipping gas-powered lawn equipment to CA now.
If a business is so small that this would be hard to manage, then they're probably not big enough to have MBAs rubbing their hands and implementing impossible to cancel systems. If a business is so big that it can afford to pay call centers to deal with their intentionally Kafkaesque cancellations, then they can afford to deal with the regulations. They can't as easily afford to lose 12 million customers.
Easy canceling is far, far easier to make than the stuff these regulations target. No honest mom and pop shop is losing sleep over this.