Electric/hydrogen vehicles aren’t really zero emission. Their emissions are at easier to control, generally more efficient facilities that are going to get “greener” in the future.
Generally speaking, electric cars are powered by variable power because they aren’t base load- meaning they run on whatever the most expensive source currently online is. Most or all household loads are the same way with possible exceptions for refridgeration and HVAC.
They obviously haven’t thought about all of the electricity that many vehicles would be using. And all the toxic chemicals in the batteries that will have to be disposed of sooner or later. Not to mention that China and India are the big polluters, until they do something to change what little change the USA can afford isn’t going to make a big difference.