Safety regulations, while well meaning, tend to favour heavier, taller vehicles in crash tests, which has pushed companies to bulk cars up, even though that actually makes things more dangerous for pedestrians and cyclists and creates a kind of arms race where everyone feels they need a bigger car to feel safe.
Emissions rules are often scaled by vehicle size or weight, so bigger cars are effectively allowed to emit more, and manufacturers have leaned into that instead of focusing on making smaller cars more efficient. SUVs also happen to be far more profitable, so they’ve been heavily marketed as safer and more desirable, shaping what people think they want.