I have plenty of friends who have kids, do gardening etc and don't own a car (or even have a license) in Helsinki.

Most people in Helsinki live in apartments so construction etc is not an issue. If you can afford a house in Helsinki, car ownership is not a significant chunk of your budget.

And I have plenty of friends who do have a car for kids etc, but only one car per household. Which is not viable in many places in the world or even elsewhere in southern Finland.