I live in a city of 60,000 people in Colorado. The closest train station is 15 minutes away, by car. There is a bus that will take me to the train station, but it's an hour to walk to the closest one and the bus comes once an hour, 6 am to 7 pm, M-F. I can't afford to spend 4 hours on a quick trip to the grocery store and never leave my house on the weekends.
There are bike lanes on the main roads (4-6 lanes 50+ mph traffic). More than half the vehicles around here are massive jacked up trucks and SUVs. I have a bike, but do not have a death wish. It regularly snows, making bike riding a no-go for most of 4 months of the year.
I am very much in favor of reducing car traffic. But it's not feasible for so many people with the way cities are designed and the lack of public transport.