States could harmonize laws (if they wanted to).
https://www.estartcoalition.org/
I suspect eSTART is... a start to what you're looking for.
So many Californians live in valleys that trap pollution. Strict emissions regulations have an immediate, tangible impact. South Carolina doesn’t have the same local issues and their standards vary. Likewise, tint stuff is mostly a police / safety issue, and is more of a problem in major metro areas. High tint is an issue in the Bronx. Not so much in rural Alabama.
I’d argue that the worst part of the system we have now is that we have a weird hybrid as disenfranchisement has become a political priority. Integration between states is driven by compacts between states and Canadian provinces and mediated through private entities like AAMVA and NLETS. That has facilitated other sharing agreements with insurers and other entities that is a serious and significant privacy violation.
We should be able to get a free passport card for identity, and make driving privilege licensure, vehicle registration, etc a purely state matter.
I wear a cheap disposable N95 mask when I walk along busy streets, which filters out probably at least 98% of the particulates. (The "95" in "N95" stands for 95%, but that is 95% of the particles that are hardest to filter: both smaller particles and larger particles are easier to filter. So since it is quite unlikely that all or most of the particles produced by brakes and tires are precisely the size that is hardest to filter, I estimate that my cheap $2 mask that can be reused for dozens walks is probably filtering at least 98%.)
In contrast noise pollution and tailpipe pollution and fuel-tank-evaporation pollution are much harder to filter (at least for pedestrians on the move) so a drastic reduction in one and a complete elimination of the other two is an extremely welcome development.
Specifically, the gaseous pollution from tailpipes and fuel tanks is composed of many hundreds of different compounds, many of which can be effectively absorbed by filtration media, but many of which cannot be. I don't bother to try to filter out this kind of pollution (i.e., gaseous) when I walk along busy streets because the filtration media makes the mask much bulkier and heavier than my N95 masks are and because the filtration media costs more (even plain activated carbon, the cheapest and most useful media for gases) and remains effective for a much shorter duration before it must be replaced.
We won't even be at 50% electric in 5 years. I doubt we'll even be at 50% of cars being sold being electric in 5 years.
There's a reason there are 50 states and not just one federal land. The needs of the people of Montana are definitely different than the needs of New Yorkers, so expecting the two states to have the same laws is just illogical. It's also why things like the electoral college is a thing to prevent the population centers dictating what the rural people have to do.
Plenty of other countries with rural areas seem to do fine without one. They also usually have much better / more granular representation, instead of a hard cap of 435 for a population that is orders of magnitude larger than at the country’s founding.
That’s why the more reactionary elements in our society have placed such a priority on making the federal government ineffective.