It can be argued that Audacity already has support for the foot pedal. Any software/hardware combination that can press the "P" key will cause Audacity to stop immediately, ready to pick up again at the next key press.
Since each pedal and computer is different, someone has to design the interface between them and the "P" key.
We have enough trouble keeping Audacity from flying apart as a simple sound editor, that's a little out of our job description. Are you volunteering to design it? The Audacity production team are all volunteers and we welcome newcomers. You can even find a designer and we'll welcome them, too.
If you're talking about serious transcribing tools, like backing up several seconds at the key press, you're right. We don't have that (that I know of). I'd be surprised if that wasn't a Feature Request.