Just for clarity, I don’t think I would draft a stranger on busy streets – or certainly not anywhere near as closely as I would on quieter roads. Not that I would draft a stranger anywhere near as tightly as somebody I know, or on a club run/audax/sportive. I would also try and communicate my presence – if it was clear they were uncomfortable I would back off (or just accelerate and drop them 😉 )
It isn’t the same as tailgating a car though, because even on the recent club run I did where I hadn’t ridden with any of them before, I often sat very slightly offset – mainly so that I could see the hazards in front better, but also doing so allows you to avoid them if they do brake suddenly. Though even if you do sit right behind you can still see the hazards better than when tailgating in a car, and provided you’re not inches away you should still be able to avoid running into the back of them by moving slightly sideways, something which isn’t possible in a car. I’m actually kind of disappointed in you directly equating bike riding to car driving 😉