If every scooter rider in Taipei had a car, the city traffic would move a meter a day.
It's also about convenience, btw, not just cost. It's basically impossible to park a car here. Scooters are also difficult but at least possible.
A huge chunk of people here just take public transit now, as it should be.
This makes everything so far apart as to make walking inconvenient. Add in unbearable weather for half of most years (whether hot/cold), and it just isn't convenient to grab something "on a quick walk" from the grocery store that is miles away from most homes.
Thankfully (some) cities are beginning to realize this, and are changing (IMHO: stupid) zoning/regulations. My favorite example has been of my own hometown's (Austin) reduction in required parking spaces for most commercial activities. This increases density, and encourages more walking. ATX's buslane-onlies leave a lot to be desired... but at least they've gotten rid of (most) downtown oneways.