Condo towers? The suburb I grew up in was all single family homes with 2-car garages, 6,600 people per square mile and 14,000 people total. We have one high school in the center with ~900 students. Walkable for all of them. There are two elementary schools around half that size with even smaller coverage areas.

We were unambiguously a suburb. 1/6th that density would have been nightmarish sprawl. Berkeley, also mostly suburban, is 12,000 per square mile! That’s my point.