It isn't "asking" anything. It providing a service for a FEE not for free. And the whole "liability" bit is horseshit. The manufacturer is liable for tire defects, the installer is liable for defective workmanship. Where the tire was purchased is irrelevant. I did business with a shop some years ago that would mount the tire for free if you bought it from them (and brought in the wheel). If you brought the wheel and tire they would charge you. If they had to take the wheel off the bike they would charge you but in no event would they allow you leave without at least trying to get some of your money. AND, if you showed them the tire and price you found on line they would almost always match it (and mount it). They are still in business while many others have failed. There are businesses that take the "all or nothing" approach. From me they usually get nothing.