Driving everywhere has the collateral effect of ensuring that people get less exercise. Mexico has an astonishingly high obesity rate (a bit higher than the USA last time I checked), and this increases the risks of many non-car-related causes of death (and illness).
Yeah, I’d buy that car-dependence is a problem there, especially for older people.
Though, in Ireland, for instance, the worst parts of the country for car dependency would be close to as bad as the US. Their life expectancy is a little lower than the national one, but it’s not dramatic, and certainly not as low as the US one. There’s something else going on.