Americans would probably do a far better job at reducing gasoline consumption by driving reasonably sized cars.
Now I have two kids and a large (but not largest) SUV. You get one cuz you need one.
You chose to prioritize your comfort over other peoples safety.
My ford edge on the other hand is much safer and can actually fit the legally required seats for my kids. So I need one. Don’t care what you think.
You don't actually need one, I don't know your situation but this is the objective truth for most people. I've raised 4 kids with a 2-door hatchback. I couldn't buy any seat off the shelf, but they've all met the legal standards and performed well.
Worth noting that the Ford Edge is also still relatively medium-sized compared to some other American trucks/SUVs. There are stock pickup trucks that I'd literally need a step ladder to see inside of the engine compartment.
But the soccer mom stereotype is also real and more families are both busy working parents so it isn’t uncommon for one or a few people to fill all three rows with kids for transport to their sports activities.
It will take a long time to undo, but there are billions of people living in communities that don't require any car, let alone some 3-4 ton monstrosity (~80% of the world owns no car at all).
Previous to the race to drive the biggest car on the road, even in the US cars were not as large. The common refrain is that safety features inflated the size, which is partially true, but wildly overstated considering there are plenty of smaller cars available today.
There's nothing special about the US that makes cars a requirement by nature.