I imagine that thousands of people have contributed to such an archive, so the number of different recordings would soon add up as an immense archive. Restaurants might well use similar sources of music for all I know, but not sure if that would account for sameness, other than it will play a recording in a similar genre or from a similar artist after your selection, presumptuously assuming you might want to hear say something by Steeleye Span after your requested Fairport Convention.