Earlier quoted context omitted.
The Ford Focus is still a 3000-pound car these days. Even "economy" cars these days are rather heavy, and you'd be surprised how little those 70s cars weighed. Old Mustangs are positively lightweight. While the land boats are mostly gone, cars in general have gotten larger and especially heavier, even with lightweight technologies and materials used to offset the increase. The way I read it, the OP was talking about…
Just like a bicycle. Which are also booming. And which are also dangerous to ride on the road with any car. The argument I was addressing was, if its really an arms race, then no way we would go from the 4800lb Ford Thunderbird to the 2600lb Ford Focus in a generation. Folks have by and large opted out of the arms race. For better and for worse.
The 4800lb Thunderbird buyers aren't buying cars; they're buying SUVs and crossovers these days.