Depending on the age of the children they can also take public transport on their own, so can the drunk, elderly, and disabled.
(Kids are so overprotected in this age - freedom to travel on their own on bicycles or public transport is great!)
These people may not be able to drive cars. No, they can't get a self-driving car trip for $1.50 yet. When they can, we won't have enough road space anyway (one 8-carriage Sydney train carries 1200 people, that's a long line of cars!)
I really like what Citymapper is doing - augmenting buses with modern tech, similar to Uber Pool but coming from the other direction: https://medium.com/citymapper/good-bus-part-1-3-77d65e6f8ce3
Of these, b) is the least common, but for these people public transport works well. From our previous house, we did this, I took both kids (5 and 2) by bus with a jogging stroller to and from daycare every day. This was approx. 15 minutes faster than going by car, due to dense traffic and very limited parking spaces. Now we live close enough that we bicycle instead.a