Sorry to disappoint you Sierraman, but the fact is that these are not charities but professional trading arms of a charity. The manager of the shop is a well paid employee of the company which runs the shop and is expected to produce a high profit in the shop. It is only after staff costs, expenses, rates and any other costs are deducted, that any "profit" is passed to the charity.
The charity may benefit in the long run, but the shop's sole purpose is to make money like any other high street store.