The big issue here is up-front costs vs distance-dependant costs.

A car costs a boatload of money up-front, while very little of that cost is distance-dependent. Depreciation, tax, maintenance, all that isn't paid when you take a trip to the city centre. You pay all that up-front or on a fixed schedule, and the only thing you pay semi-frequently is fuel, and even that isn't paid on every trip. So while it's super expensive, it doesn't feel super expensive.

Public transit on the other hand is often paid per trip, and then you see the total cost of that trip and it feels super expensive.

If you want to get people off cars, you need to provide a solution where they don't need to own a car. Because if you own a car, using it isn't all that expensive any more.

That's why all forms of alternatives need to work together nicely:

• You need good, safe bike infrastructure for on-demand comparatively short trips. If it's <10km, a bike is most often faster than public transport, but after that it gets slower, it gets exhausting and that becomes a hurdle for most people.
• You need good, safe public transport with a cheap year pass. Public transport needs to be on a level where you can just walk to the bus/tram/metro stop without looking up departure times beforehand. For that, public transport needs to come every 5 minutes or better. Year passes allow you to take public transport without worrying about cost.
• You need good and fast high-speed trains for regional travel. Even moderate high-speed train projects easily exceed 200 or 250km/h and are thus far faster than cars. The last mile is still a disadvantage for cars, but if the train can make an 8h car trip in 4h, then it's still worth taking the train, even if you have to make your way to the train station first.

If one or more of these parts isn't working, then people will still own cars, because not all of their use cases are covered. And if people own cars, then they will use them.