I think you need to check your math. There are 14 times more of these electric mopeds, etc than cars, but they only have 4x more impact than the EVs. So one EV displaces about 3.5x more carbon emissions than the mopeds.
To make the 2030 halve our emissions deadline, and 2050 net zero deadline with just little city vehicles, we’ll need to abandon the suburbs, exurbs and rural buildings and infrastructure that we already have, and replace it without producing any additional emissions. Also, in the US, most cities that experienced significant growth after ~ 1950 need to have their new parts razed and rebuilt to accommodate public transit routes and add walkable amenities.
None of that can possibly happen at sufficient scale in the next 7 years, and it certainly would have massive environmental impact if it did.
Alternatively, we could switch all cars to EV’s, use existing construction and infrastructure, and get a > 75% reduction in transportation carbon, even without cleaning up the power grid.
In reality, we are already cleaning up the grid, and time of use subsidies are doing a good job of moving time-shiftable demand to high-production times, when the grid is cleaner.
EVs are currently one of the biggest, easy to time shift loads.
So, we can have a 90% solution to transportation carbon, or go for a 97.5% improvement (rounding the 3.5x improvement moving to mopeds would give up to 4x), but then emit way more carbon than total transportation emissions while we rebuild an unprecedented number of cities all at once.
I’m all for public transit, and think all new urban / suburban housing should be built along high capacity transit corridors, but doing that isn’t going to solve global warming in time.