The buyer can change his shipping address on PayPal for every buy if he wants to. It is the PayPal address that a seller ships to not the eBay address. I sell everyday on eBay. If I had to guess about 20% of the eBay addresses do not match the PayPal address. It is the PayPal address that the buyer confirms to get their goods shipped to. Totally the buyers responsibility. But as a commercial seller I always send a thank you when someone buys and pays for it on eBay and always end the thank you with
Shipping to PayPal address:
XXX XXXX
XXXX XXXXXXXX
XXXXX,XX,#####

That way if they made a mistake most of the time they will recognize it and let me know. That happens maybe twice a year.