It's very simple to do, for example via taxes, or by building the roads such that huge cars are impractical. You find very few F150s on twisty narrow Italian roads.
If lanes are smaller, then people buy smaller cars. If parking spaces for compact cars are differently priced than that for huge cars, then people buy smaller cars. Set insurance minimums for liability by vehicle class. (scale it to liability damage statistics)
There are a lot of ways to strongly disincentivize big vehicles. If we merely start making them pay for the space they occupy, they immediately become too expensive.
I think it could be done with coordinated license requirement changes. Make most trucks/SUVs require a higher more rigorous license class based on height/weight, grandfather in existing vehicles for now. But if you want to register the 2030 9 ton Hummer EV you better be able to prove you can safely drive the thing and won't park near the intersection just because it's Sunday and you won't get a ticket.
Of course that will never happen so you're right...
Likewise for roundabouts. They're putting in new ones in some areas. In other areas, there simply isn't the room based on existing buildings, etc. Not to mention the cost aspect. It might help, but it's not "easy".
GP was most likely thinking not of large roundabouts that take the place of major intersections, but the smaller traffic-calming type where the center can be as minimal as a 3 foot wide concrete block. They can be fit into pretty much any intersection because their purpose is not to change the path so much as to, frankly, eat up whatever extra space is available, which forces cars to slow around them.
Are you thinking just of roundabouts that include a raised middle and/or central reservations on approaching roads? In general, roundabouts need no more space and cost than a regular road would, see e.g. https://goo.gl/maps/Y6jzLq5SuYzMMf2a6
I have to say I agree with you on the roundabout. Nothing changes a driver's mind like a square curb. That particular intersection didn't have space though, so they installed that abomination.
Changing driver behaviour though? I'm pretty negative about it.
I get honked at regularly for stopping at those stop signs. The police head to Twitter and make fun of a few drivers a week for stunt driving. The city is opening a new processing centre because they can't handle the load of the speeding tickets from the speed cameras.
Yet I only see more and more aggression out there. People drive like they're the only ones on the road.
It's a 40 minute walk, one way, from my door to the nearest store. As much as I'd love to avoid the situation altogether, I don't have time to walk. Forcing people to drive everywhere is probably part of the problem, though.