I hadn't even thought about that breach vector! In this case they'd been living there for quite a while.

It's also pretty common for garage door installers / builders to either not change the default config or use the same one or pattern for every home. We were amongst the first to build a house in a new sub in our area so we'd go for walks around the neighborhood while the homes were being built and would go through them and of course I'd always look at the codes. The primary builder in the sub set the dip switches to the number address of the house. That provided a nice geeky / awkward way for me to introduce myself to my neighbors by opening their garage doors for them.