>No, you can't infer that it "works." Only that it CAN work. The car may be poisoning you with carbon monoxide. Your rear brakes may have become disconnected (happened to me). The antilock braking system may have a faulty sensor that only fails at very low speed, leading to them engaging when making a normal stop, but also preventing the mechanic from seeing the problem, because he didn't listen to your bug report and instead tried to repro the effect with high speed panic stops (also happened to me).

This is called pedantitic reasoning. You look like a drowning person trying to stay afloat.