The car is climate controlled, has a stereo, I can have water/food in it without needing a backpack or carrying anything, and it's sitting in a comfortable seat while I'd find a super long walk like that uncomfortable. I could use headphones while walking but something about walking feels like a constant distraction if I'm trying to listen to something. And if I'm in a car, I feel like I can go anywhere I want on a whim, while if I'm walking I'll just want to get it over with and only stop somewhere if it's directly on the way.
I don't mind walking if I want to, on a trail or something, but not if I have to. I guess I'm just not used to it and don't like it enough to make it a habit.
It depends what you're walking through! I'll walk for hours on a beautiful nature trail or a pretty, safe cityscape with interesting sidewalk-addressing buildings.
I won't walk for 5 minutes sandwiched between a fast road strip-mall parking lots, industrial facilities, or open fields.
It's exposed (to the sun and the wind) and it's dull. Inviting pedestrian environments need a sense of enclosure. Can be sidewalk-abutting buildings, can be trees, can be parked cars, can be all three. And they need stuff to look at that isn't monotonous.
Why?!