The reason for that is because the infrastructure is still designed for cars. Roads are hostile to walk next to, people literally throw things at you. You can't ride a bike half a mile because there's either no sidewalk, or if there is you're supposed to use a painted bike lane and ride alongside traffic going 40-60 MPH. At least that's what keeps people in our current suburban area (and pretty much every one that I've ever seen or visited) from walking anywhere. It just comes down to infrastructure, which is extremely weak and fragile in America by design. You can't protest what your government does when you have to find parking first. You can't boycott Russia when you depend on them for your livelihood.
You can see that this is true because when you visit an actual neighborhood there are lots of people walking around and bikes and greater levels of economic activity. I'm not sure what metro area you live in but if you live in one I bet you have an area like I'm describing. It's probably where you and your friends or significant other go out for a nice dinner. Most of the country could be like that and you could still drive your car to Costco once/week.
You're literally inventing problems to explain why people in my town don't walk to a grocery store. We have quite a few grocery store spread out. Most of the city is easily within walking distance to one. It is not hostile to ride bikes here, we have sidewalks on every street, and I've never had anyone throw anything at me. The streets aren't clogged with traffic. I even see plenty of people walking and riding bikes, they just look like they're doing it for recreation.
Well I can't speak specifically to your town without knowing where it is, but it sounds like you live somewhere similar to where I currently live, and both areas are pretty hostile to anything but driving to participate in society. One of the red flags to spot is walking for recreation and only seeing people ride bikes for exercise versus day-to-day activities.
Even if you disagreed with some or all of the things I've said, dismissing them as an "invented problem" is pretty unfair.
You can see that this is true because when you visit an actual neighborhood there are lots of people walking around and bikes and greater levels of economic activity. I'm not sure what metro area you live in but if you live in one I bet you have an area like I'm describing. It's probably where you and your friends or significant other go out for a nice dinner. Most of the country could be like that and you could still drive your car to Costco once/week.