When you think of your garage door opener, you probably well, you probably don't think about your garage door opener that much. But when you do, you should keep in mind that the signal between the remote and the opening mechanism isn't necessarily as simple as you think.
When garage door opener companies first started researching frequencies for the transmissions between remotes and openers, they quickly came to the realization that there weren't many available. They had to get in touch with the FCC to figure out which ones they could use.
The military literally had to give them permission to piggyback on restricted military frequencies. But on one condition: that they could monitor it. They would keep oversight over the frequencies.
A few years later, some homeowners near a military base couldn't open their doors. No one explained to them why, and they simple had to buy new equipment. After a few similar incidents took place, the government released a statement that their signals had to, unfortunately, be compromised such that the military could conduct radio ops testing for the Department of Homeland Security.
The military maintains that garage door openers operate on an unlicensed basis and thus are not entitled to the use of the frequencies.
Homeowners are not happy.