Actually, no. Given the state of the tech at the time and our knowledge about pollution and the effects of various types of exhaust gases on the atmosphere it wasn't true 'all along'.
There were levels of vehicle use that were perfectly acceptable. But now that transportation is a world wide commodity instead of a luxury those effects are inescapable.
So there was some point in time where the balance shifted, and then it took a long time for the reality to set in (and some part of the world are still in denial). And it will take some time still to shift to electrical vehicles, but those too have their own waste and risks, some of which will only become apparent when their adoption rate crosses certain thresholds.
People usually think cars are the biggest sources of emissions but it's not even close. All transportation (car, planes, trains, etc) represent 14% of global emissions.
Globally the biggest source of emissions is energy production which represents about 35% (25% of direct emissions and 10% of processes like refining fuel).
Electricity required combustion to produce at the time, and still does today. Battery waste is also not negligible, and battery mining is as dirty as oil.
Electricity required combustion to produce at the time, and still does today. Battery waste is also not neglible, and battery mining is as dirty as oil.
A nuclear vehicle would be impractical due to waste and risk.