Cycling and walking are active and would have a net benefit if more people switched away from sedentary driving.
Bike brakes and shoe soles don't have to slow down thousands of kilograms of mass either, so the wear and subsequent particulate emissions are much less than a car.
Driving provides far more utility than just moving a person. It moves to-and-fro many people over relatively large distances with many other objects, all on demand and on the whim of the driver.
Walking or riding a bike is nice. But they are not suitable replacements for the multitude of utility a car provides.
Sure, we'll just throw the toddler, child and his hockey gear, backpacks, the dog and the wife on a bike and drive the 3 miles to drop off the child at hockey camp, then another 2 in another direction to go to the playground (it has to be this particular playground because the one by the house is boring now) and walk the dog in the park while pushing the toddler in the stroller that we somehow transported on our bikes. And then when we stop at Home Depot to pick up a bulky and heavy items, we'll just tie that onto the bike before picking up the kid from hockey.
No, a bike is rarely a suitable solution to this problem. People want cars because they solve a lot of problems like freedom of movement at any time to any place with anyone and anything. If this was any way to live then people would actually be doing it. There's a reason MANY people move out the city when the kids start coming because subways and bikes are not very nice to manage these things.
This site is full of single dudes who live in urban areas and that's their world view. People with families do not fit into that lifestyle.
When there's proper public transport in place, cars aren't needed. Trains for medium/long distances, busses for medium/short distances, bikes for short distances and a pair of feet for everything else.
Beyond a certain network-density of other modes of transport, there are simply better alternatives to cars (in most cases).
Cars by themselves are the most inefficient (cost, space, fuel, economically) and polluting mode of land-based transport we have.
I know, it's a completely different thing in the US, which is full of car centric infrastructure and other modes of transport are either absent (passenger trains) or often impossible or outright dangerous due to the sheer danger caused by a lack of proper infrastructure for pedestrians/cyclists, public education/general behavior (road rage, drivers' education, ...) or even impossible to cover by bike due to the distances caused by urban sprawl/a lack of density due to zoning laws.
Man wanted to travel larger distances in shorter time to any place he deemed worthy at any time.
And after a while another man came and said "you shall not, its unhealthy. Take a train, which will bring you to a limited amount of places at certain times during the day. Ah and don't forget to pay your bike ticket because a bike is obviously a person as well"
Bike brakes and shoe soles don't have to slow down thousands of kilograms of mass either, so the wear and subsequent particulate emissions are much less than a car.