European cities were especially bad because the EU pushed diesels while having significantly less emissions controls than gas vehicles until the mid 2000s. Most of the vehicles impacted by ULEZ are those same diesels.
I love when people bring up the kei truck argument. If all you do is haul mulch around town from Home Depot, by yourself, and you already have another car, sure, go for it. But pretty much nobody owns a key truck as their only car. There's little crash safety, your knees are the crumple zone, they're not designed to go on 70 mile interstate highways, you usually can't transport many people. I would feel uncomfortable transporting friends/relatives more than a few miles on low speed roads in a kei truck, because they're 25+ year old designs focused on size rather than safety.
A kei truck is a supplementary vehicle at best... so you'd still want a car, and then you have two vehicles. Lots of people don't want two vehicles when a single vehicle that covers both use cases exists.
Sure, nobody needs a gigantic beast, but for people in lots of parts of the country, the downsides to owning a larger vehicle aren't that big. Why buy a smaller pickup truck when a full size truck is just a few thousand dollars more (in a country where the average new vehicle sells for $50k), gets similar fuel economy figures, and has more room in general?
For a while, women in cars were more vulnerable than men in cars, in part because crash test dummies were sized to typical male proportions, and cars are built to pass crash tests rather than be as safe as possible for all occupants while still passing crash tests. This sometimes led to things like airbags being placed in locations that worked great for average height men but not as well for average height women.
I don't know if it's fair to say that women in cars are just as vulnerable as men in cars, the same goes for the pedestrian argument.
It seems like you're using "women" as a proxy for "smaller people". Children and small-statured men are just vulnerable as women in crashes. Regardless, we now do crash tests with a variety of body types.
A 5-foot man is just as vulnerable when being hit by a car as a 5-foot woman, and obviously children are much more vulnerable than grown women when being hit by giant vehicles.
One thing I noticed as soon as I bought my large, offroady SUV (never having driven an SUV before) is that other traffic treated me much more respectfully. When I was in a compact sedan, traffic would swerve in front of me much more often, people would refuse to let me merge, drivers would ride my bumper, and so on. All of those things still happen, but much, much less frequently. For inattentive drivers, it's more difficult to ignore an SUV, and for angry drivers, it's more difficult to bully me around. And yeah, many of these bad drivers are in SUVs themselves, where it's easier to miss a nearby sedan.
Am I fixing the problem by driving an SUV myself? No, but I totally understand why people feel safer in them.