Thanks to the ULEZ (ultra-low emission zone) in London, this is very much already happening — anecdotally (because I can't find any easy numbers right now, everything I can find is from 2020) a huge number of the private and public taxis in London are now hybrid or full electric.
Apparently there are already 5k TX electric taxis out there, which is a good start:
Live in central London and usually walk everywhere, never experienced or even heard of black snot. Pretty sure it’s only a thing for the tube-travelling demographic.
