We completely agree. Cars did enable that. They also caused people (especially wealthy people) to push for the very things that cause lower density, because driving through high density areas is a pain. I mean, it's not even that complicated. I used to go to my planning board meetings every month. I won't deny an agenda; I rode my Brompton to them. At those meetings people said (paraphrased but close) "We need to limit density because of traffic".

Unsurprisingly those neighborhoods have poor transit service. A shame, because in the example I think of there was once a rail line right through the neighborhood; it's what caused the neighborhood to get built in the first place.

If only _I_ decide to start taking a helicopter to work it's fantastic. If it starts to become popular to do so it will be a hassle, so people might push for rules about minimum helipad counts for buildings and building density because having thousands of people commuting by helicopter causes loads of congestion. As a result of both of those things buildings will need to be even farther apart. In fact, it might push them so far apart that it's impractical to get between them via foot, transit, or maybe even car. As a result, everyone uses a helicopter to get anywhere now, except for the poor chumps who can't afford one and are stuck driving.