Undoing our mistake is always an option.
If you want to make wholesale changes quickly, you probably need the support of voters.
Nobody put 240V center-tapped, 60 Hz AC residential electricity to the voters either, but if you wanted to change it, you're probably going to need a strategy and a communications campaign to explain why and how.
I will not take my kids on any transit where they might be assaulted by a naked homeless man. America will never have safe public transit because it lacks the will to handle the mentally ill and addicts.
Thankfully in Australia's biggest cities our public transport systems are generally clean and safe to use - but a) they're not always super reliable, despite some improvements in recent years b) they're often poorly interconnected, meaning I could potentially do 80% of the journey sitting in comfort on a train, but spend 3 times longer than it would take to drive trying to deal with getting to/from train stations and c) there are still huge areas of said cities that are fairly poorly served by trains, and buses will always be a second rate way of getting around. Oh and d) you can't carry v. large items or animals on most public transport (*). All solvable problems, some easier than others, but there's a distinct lack of real political will to do so.
(*) e.g. it'd be a 15 min train ride to take my dog to the beach from where I live, but she's not a service animal so wouldn't even be allowed on, despite taking up less space than a human.