Actually, the remote transmitter doesn't work like that. And even if it did, having the ability to open the windows would also mean having the ability to unlock the doors and start the car.
Automobile remotes, both keyless entry and keyless start fobs, all work the same way. The remotes are not programmed to match the car. The CAR is programmed to match the remotes. This is why you can change the battery in your remote without having to reprogram.
You can't just figure out a code and get access to the car. The car has to be set to accept commands from any remote being used on it. Remotes have unique (within limitations, obviously) codes, and the car looks for that remote's code before accepting commands. It's not the other way around, as many people assume, with the remote being programmed to send the code the car wants. Some fobs use rotating codes, which make things even more difficult.
And with modern push-button start cars, most remotes must actually be programmed by a dealer or locksmith with access to tools that can interface with the car's security system. They have to plug into the car itself and program the fob.
Definitely nowhere near as simple as grabbing a laptop and looking up a code.
