If you're challenging my assertion that there was a noticeable improvement in air quality in Pittsburgh when the diesel busses were not on the road due to the driver strike, you're wrong. Diesels produce up to 400 times the amount of particulate pollution vs. gasoline engines. Mass transit busses remain on the roads all day and most of the night, unlike a commuting auto, which is normally used an hour or two per day. There was a significant improvement in air quality when those diesel busses were not running - it felt literally like a breath of fresh air.

Busses running on natural gas would be a big improvement for urban areas, and it appears natural gas is being used more frequently now.

As for needing it adopted by everyone, you go right ahead. The less time I have to ride around in a closed enviro with every kind of virus carrying, shower-phobic, alcoholic, tourette syndrome suffering mental case in town, the better.

My point isn't that mass transit should be ignored, or that we shouldn't look at doing it in a more effective way where it makes sense, but that wide scale mass transit that has as a stated goal of replacing the automobile in most circumstances, even in rural America, would not be advisable. There are about 303 people per square mile in France (non-euro territories not included), compared to 33 people per square mile in the US (excluding Alaska's area). I've excluded the no-mans-land of Alaska from this equation, but even if you excluded all of the areas where nobody lives in America, you'd still have a significant density difference between France and the US. The issue is not the same here as it is there by a large margin.

The other things is, I was in Pittsburgh in the early 90's during the Port Authority strike - no busses or trains ran in Pittsburgh for a week or more. What I recall is that people found ways to get wherever they needed to go, the air was SIGNIFICANTLY clearer and cleaner without all of the diesel belching busses on the road, and even though everyone had to get to work by private vehicle, traffic moved BETTER, because the slow-assed busses weren't clogging traffic up at every intersection in the city during rush hour.

Regarding the US: Mass transit is fine for many but certainly not all people living in urban areas, a lot fewer people who live in the suburbs, and almost nobody who lives in rural areas. The nearest grocery store to my house is 18 miles away. Mass transit would be an extremely inefficient method of transport out here. Either you'd have to eat a really, really big cost-per-ride bill while providing some semblance of decent and frequent service, or you'd have to provide really, really poor, infrequent, PITA service for a more reasonable expenditure.

It'd probably be different if we had population density/distributions similar to Europe, but we don't.

Cars will remain with us for a long time.