I tried looking for it and I found a YouTube video of some Indian street vendor doing it, but iirc my old video had been of some British guy. There's more than one apparently.
The loss of sensitivity doesn't happen all at once, plenty of cooks and serving staff have much higher tolerances than non-cooks/waiters. I'd expect that this is at least partly from damaged nerves, but while they have reduced sensitivity, iirc then the British guy said that he had lost all sensation in his hands.
The evidence of studies says that you are wrong.
Here are some key points from a study summary that was made for London: 20mph zones do not appear to worsen air quality and they dramatically reduce road danger. They also support a shift to walking and cycling, generate less traffic noise and reduce community severance. In 20mph zones vehicles move more smoothly with fewer accelerations and decelerations. This driving style produces fewer particulate emissions.
https://content.tfl.gov.uk/speed-emissions-and-health.pdf