Other than that, there's plenty of public transportation.
And you don't even have to make the entire city center free of cars, i.e. make every 5th street available for cars (limited, like 1 open lane). As long as you can walk a couple of blocks you'll be able to grab a taxi.
I agree with your point in theory, but it’s somewhat ironic that the Oslo bike share you link to is closed for the season. There are ways to move around without cars, but it becomes far more challenging in winter climates
Other than that, there's plenty of public transportation.
And you don't even have to make the entire city center free of cars, i.e. make every 5th street available for cars (limited, like 1 open lane). As long as you can walk a couple of blocks you'll be able to grab a taxi.