but this issue of “zilzul shabbos’ is -bemechilas kevod hatorah- a new invention
Just how new do you think it is?
It’s amazing how some of the greatest poskim have discussed how serious an issue zilzul Shabbos is, yet you have the chutzpah to dismiss it “bemechilas kevod hatorah” (sic).
If you allow escalators and Shabbos elevators, I do not see why public transport- especially beshaas hadechak- would be ossur.
We aren’t mattir elevators and escalators. Public transportation would probably be worse, though, because it’s more public, and because it is more likely to lead to the erosion of shmiras Shabbos, ch”v.