The first electric garage door opener dates back to 1926 when C.G. Johnson invented it in Hartford City, Indiana. You could open the door from a switch, either inside the garage (we still use those today) or outside, even on a post so you didn’t have to even get out of your Model T. In 1931, two teams, one in Illinois, the other in Washington State, both invented wireless garage door openers.
The first remote openers were simple and consisted of a simple transmitter (the remote) and receiver which controlled the opener mechanism. The transmitter sent a designated frequency that the receiver is listening for. The only problem was that you you open neighboring garage doors as well.
The second wave solved this issue by by transmitting a digital signal and the receiver is only responds to that code. The codes were set by eight to twelve DIP switches on the receiver and transmitter, allowing for 28 = 256 to 212 = 4,096 different codes. Just use a different code
if you door just happens to be on a close neighbor’s code. Crooks always find a way so they could use a black box master key that automatically transmitted every possible code. A latter development would use a frequency spectrum range between 300-400 MHz and rolling code technology to defeat code grabbers.