Why do ESC and other electronics components in a mini quad typically come with the signal and ground wires twisted together?

As far as I know, the ground wire shields the signal wire from outside electrical interference. Electrical interference can corrupt data in the signal. The ground wire helps protect the signal values from being altered.

I have always twisted my wires but not for this reason. I did it to clean the build up as I honestly had not idea there was a positive reason to do so. But now that you guys are all saying the real reason for it, it all makes sense why some people that have almost identical builds as I do have lots of video noise and can't seem to tune as easy. Hmm I was smart and didn't even know it. And most of the people that I see that just let the wires hang and not twisted seem to also bee the ones always wanting to add caps for poor video.

Twisted wire pair is less prone to interference. As a bonus it also causes less interference to other equipment.