Paris is definitively livable without a car. The RER, trolley, metro and bus network is so dense that it absolutely makes no sense to use a car (this is far more longer, dangerous and stressful to use a car), even when you live in suburb. I do live in Paris suburb. People just got very bad habits, but they could manage to change it through education and state promotion like this day. This day was not enough though, and it should be a reccurent event, I mean not yearly but monthly or something.

> But lots of people live in a walkable/bikeable distance from a station

In paris itself yes, but if you live in the suburbs last time I was in paris there weren't really large and convenient parking options on the outskirt of the city itself, so you couldn't trivially leave your car and hop in the underground or a bus.