> The more people drive, the less amenities need to be near them, the more space is taken up by roads and parking, the less walkable the area becomes, the more people drive, and so on, until no one can walk anywhere. We have to be cognizant of that and make sure it doesn't get to that point.
But why? You seem to assume it to be universally accepted that everyone wants to live in walkable places, but the evidence in front of you is simply contradicting this. People routinely move to non-walkable places by the millions, with the expectation that they will be driving everywhere, and they don't mind it at all. I think you are so deeply emotionally embedded in your anti-car lifestyle (especially given how you describe them as "scary, noisy nuisances") that it might be hard for you to conceive that people might prefer this to the alternative you describe.
> Part of that is making sure that e.g. as many people as possible have daycares at a walking distance from them.
No, because it is very much unclear that people actually want that more than other things. If you ask people whether they want to have a nice daycare in a walking distance, most will answer "yes", this much is true. However, this is not necessarily compatible with many other things people want, like, for example, big houses, low costs, low noise, low traffic (including public transit and foot traffic), or generally living in a place with fewer people and less churn, so that you can actually get to know your neighbors.
Given all these preferences and constrains, what most people are aiming for is a satisfactory trade-off. Your proposal about making sure that as many people as possible have daycares at a walking distance from them is basically trying to force on them your preferences, and ignoring the trade-off that they choose.
Going back to your description of this vicious (to you) cycle of car-centric lifestyle, I can also describe virtous cycle, where a walkable place pulls more people into it, resulting in more businesses and amenities setting shop there, which pulls even more people, and adds more transit options which are now economical due to existing density etc. Now imagine that someone helpfully tries to "make sure" that as many people as possible have a car parking spot close to where they want to be, and institute parking minimums on businesses. After all, if you ask people whether they want to have cheap and plentiful parking anywhere they need to go, most people will answer yes, just like when asked about daycares within walking distance.
Of course, as you almost certainly realize, you can either have daycares in a walking distance, or free and plentiful parking everywhere, but not both at the same time. Thus, if you understand the mechanics of this, you'll oppose the parking minimums (which, by the way, I oppose too). However, for the same reason, many people will oppose your plans of densification and daycares at walking distance, because they simply don't like it as much as they like other stuff, and they understand that there's a trade-off involved.
> But in the grand scheme of things, it highlights a problem. Let's keep it in mind, you know. Let's try to solve it at some point, maybe.
Yes, let's keep in mind that there are trade-offs, and figure out a way to eliminate it, so that people can satisfy more of their preferences. Often technology helps; for example, cars eliminated huge part of a trade-off between being able to live in calmer, less dense places, and access to amenities. Future technology might help here in other ways.