Anyone with a remote car lock has wondered at one time or another whether the signal is really one-of-a-kind. What are the chances that your keyless entry could unlock someone else's car? It turns out the odds are pretty slim.
Mental_floss explains how the coded radio signals work on a keyless entry and why the odds of unlocking another car are so small. Link
Modern remote keyless entry systems are pretty secure, but there is a slight chance Jason could open another Camry if he wants to walk up to one and press the unlock button on his remote (assuming it uses a 40-bit code) one trillion, ninety-nine billion, five hundred eleven million, six hundred twenty-seven thousand, seven hundred and seventy-six times, running through all the possible codes his remote could transmit until one works (assuming he can hit the button once every second without taking any breaks, he’ll need just shy of 34,842 years to do so).
Mental_floss explains how the coded radio signals work on a keyless entry and why the odds of unlocking another car are so small. Link
Still, with modern transponder technology you still won't get the car started.