I really doubt you would ever license any specific songs as a cafe business. You should be able to pay a fixed fee to a PRO and have a blanket license to play almost anything. Is it so expensive in the US, or perhaps they do not know that this is an option? If the former, and those cover artists help those bars keep their expenses low and offer you better experience while charging less—working with the system, without ripping off the original artists who still get paid their royalty—does it seem particularly parasitic?