You are assuming the minimum wage summer jobby kid would actually take the bicycle apart and go through every nook and bearings. Right. You do know that bicycles arrive at LBS mostly assembled to right? Perhaps if you spend $$$$ on a carbon bike you may get a more experienced tech to go through it. But don't expect that kind of detail on regular bikes. There's a thread about how much a the wages of a bike mechanic vs. T&L to ensure profitability.