EVEN a mechanic cannot tell you if a car is a lemon or not before you buy it?

So , if you are planning on buying a used car , what if you want to have it looked at by a mechanic first, you think this is the right thing to do? Well, a tear down and re-embly of the transmission alone will run between $500 - $1000, to inspect the transmisson, which is a major part of the vehicle where drivers often need repairs. Anyone who knows anything about cars, knows that , no matter how many transmisson shops you go to, NO shop will give you a free tear down of a transmisson to inspect it, so there IS NO way to be sure that any used car is not a complete and TOTAL piece of junk is there? There is no certainty, correct?