It's generally easier to envision a small amount of changes at once. But for something like walkable or bike or public centric transportation, multiple things need to change before it makes sense.

Ie with a car, you go to grocery store once a week. You buy lots of things.

If you live close to a store in the city, you can just pick up something while coming home, or even when you're cooking you can just run to the store in 2 minutes to get something on-demand.

But you can't gradually go from one to the other so easily. You can't go with car to the local small store. There's nowhere to park etc. You can't go to the big box store in the middle of cooking because it takes an hour for the round trip.

So if you have person doing A, they see B as impractical "where would I park?". Or person B would say A is impractical because "I'd have to know cooking a week in advance". Both arguments are correct, you can't go from A to B or B to A by just changing one thing. You need a whole new big picture.

You can still do a mix sometimes, ie a person can do both, but not in the same situations.