[p_l]

You're missing how some of those places were built with, or without, the necessary secondary support architecture that was specified in the original ideas.

For example, Communist-era housing blocks in Poland had standardised requirements for availability of grocery shops, healthcare, transportation, sport and recreation areas, etc. for each community built this way, and generally you never had to walk far to get to a grocery store in my experience. What was problematic is that due to worse processes at the time, it took years for green areas to get, well, green.

Corbusier and many places inspired by him seemed to have put the requirements, but often for various reasons those were stripped out - either due to subpar followers, or costs, or even outright malfeasance (one place I lived in had the design changed by builders while architects were on vacation, resulting in much maligned building)