Let me ask you this.
How much have you perceived that you lost out on in ever buying a part paying between 3% and 4% on the sale of the part?
So what?
You sure love to make a mountain out of a mole hill.
Next time you see someone asking 4%, look to see if they are a Canadian.
Pretty sure they get dinged more from Pay Pal, because a USA sale is considered a foreign transaction.
Maybe asking, to cover their *** on the sale.
Dunno.