I find this very hard to believe and quite annoying. At the same time though, It would be spot on for me cos I would not want to pay extortionate prices for a silly service when I can do it myself.
My solution is service the car Myself and staple all the reciepts of the oil, oil filter, pads, plugs etc etc etc into the service book with the dates etc on the reciepts.
When it comes to sell the car the buyer will think what is the point of buying all the stuff just for proof and not fitting it anyway so hopefully will be happy enough!!!