Never heard of a switch/brake system needing a "reverse" voltage to shut off. All of these mechanical switches AD/TF are the same. They are just momentary, normally closed, switches. Maybe it's a hint that, after all these years, the brake light switch on many vehicles is still a pedal activated mechanical switch.
Some of the aftermarket switches are different, I believe. Some make a connection and some break a connection. Just need to be aware what you're buying if you're doing a custom install and that it suits your needs.
