Ridiculous thing to say. Suburbs, as a consequence of their low density, must have bad or nonexistent public transport - unless you somehow finance a billion busses driving idly around. Old and big European cities achieve good public transport by having people not live in suburbs.
Please note the silent car-centric in front of "suburb" here.
Suburbs used to be different pre-WW2:
* https://en.wikipedia.org/wiki/Streetcar_suburb
* https://www.youtube.com/watch?v=MWsGBRdK2N0
More generally it is sprawl—when residential is not with-in walking distance of commercial—that is the problem. You want to have cars be optional and not mandatory.
Also, "density" ≠ Manhattan/Hong Kong:
Yeah, and that sucks. Even in Europe, areas that have money and space to build have adopted pretty car-dependent layouts. In France, 70% of people outside Paris and Lyon drive to work: https://www.fleeteurope.com/en/smart-mobility/europe/feature...
I don't see a problem with this. You use whatever works the best, and for smaller cities and towns that's going to be a car. Public transport only starts to make sense above the 1 million inhabitants mark, and even then it doesn't really get good until 2-3 million.
I live in the Netherlands. Most major cities and smaller cities has good public transit and walkable centers. Not even Amsterdam has one 1 million inhabitants.
The general consensus about urban design suggest it's all about density, mixed zoning and separated bike paths and traffic calming.
And by not having huge empty spaces between houses, wide roads, 2-garage houses with long driveways. Ultimately, it's a different geographical and historic reality.