As a vendor myself, no matter if you are paying via Paypal, or with a credit card directly, there are still fees involved.
Depending on the Credit Card Merchant plan the vendor has, the fees can be more or less the fees paid by the vendor through Paypal, my merchant fees are less by about 1%, so it actually costs me less when a customer uses his credit card, vs Paypal.....however having said that, I personally don't care which method of payment the customer chooses, as it is my feeling that it is the cost of doing business, and all of those fees can be chalked up to business expenses when it comes time to do your taxes anyway, so in reality, the vendor isn't loosing anything, as we get most of it back in the end game through taxes.
Personally if I buy from some place, and the they want extra for Paypal fees, then I go somewhere else, or choose another form of payment. Problem arises with some of my suppliers that they will either take Paypal, or a bank transfer, which can be a PITA to do at a bank as you need an appointment, and when your shop is open pretty much the same hours as the bank is....hard to get to the bank to make the transfer, so sometimes Paypal is the only option.
Anyway, long story short, Paypal and Credit Card Merchant fees, to me at least, is just the cost of doing business as a vendor, and should not have anything to do with the customer. I don't recall any transaction I have done with Paypal where the customer has been made to pay an extra fee for using it as payment, it should all be on the vendor. The one exception is if you are sending money "personally" then you have the choice to pay the fee, or pass it on to the person received the money, but for retail purchases, the vendor gets the fee.