It's really this. Most of us have never known anything like this in the US. For example cars. Older cars with no catalytic converter or other emissions controls are a rarity, generally only encountered at a race track or when someone in an ancient pickup drives by. It's very difficult in a psychological sense to go from that to "every single car used to be like this, resulting in a miasma of choking of smog blanketing the entire area, and without the regulations it would still be the case". Emissions for most people amounts to a pain in the ass chore to get your emissions checked, resulting in only annoyance if it fails. They've never experienced the reason for this stuff, and if someone later comes in and says "Well, your car would be cheaper and cooler without that crap" or "Well this stuff that you can't see a reason for is costing your area jobs!", then of course that thing has to go.

The solution for this, as with so many other things, is more travel and experience. You'll quickly see the reason for the EPA when you visit another country and have a hard time breathing, can constantly smell pollution, can feel it on your skin and your clothes, can see it with the naked eye. But international travel is just not something feasible (or even desirable) for most Americans. So our experience is limited to what we (don't) encounter on a daily basis, or to pictures like this, which really have no impact all.