It's not only major cities that ought to have good public transportation. Basically everything except small villages and rural communities would have all that in a sane world.
But yes, over 80% of the population of most developed countries live in a city.
Not everyone, but most people live in major cities. And any city that is big enough to "justify" building stroads is absolutely big enough to justify having walkable communities connected by light rail or bus
All but two of my ADULT family members in New York City drive. Even though they have access to the best public transit in the country and finding a parking spot can be a chore. The rest of us (as in Americans outside of The Big Apple) are required to drive.