That said, I currently find myself in a suburb, and bicycling is actually okay. I can bike out of my neighborhood to reach the main streets, and there are actually pretty decent bike commuting paths once I reach them. If you're wanting to haul things like pets and lumber, recent cargo e-bikes can haul a lot. They're expensive, but they exist if that's a priority for you. I think bicycles can be a pretty decent option for people in the suburbs, at least sometimes. Plus, bikes are just fun!
That said, using my car less is a big goal for me, so I sometimes take the less convenient option. My longterm goal is to find a way to leave the suburbs and live in a city, though, so I can be much less card-dependent.
A subway could be dug under everything, but the $$$ are too high. A gondola system could potentially go between houses and so serve a few cul-de-sacs before coming out at a suburban station - this looks like the lowest cost answer, but it still isn't cheap.
And many suburbs in the USA are actually technically their own towns, some older, some younger, and you can walk around just fine if you plan a bit and want to.
After all, if you live in a town of 10k people almost by definition you can walk everywhere that is available.
Then the busses can stay on the straight main roads while all the cars go get lost in the culled sacs, while people walking or on bike have direct paths.
Some studies show people will walk 3/4 of a mile, which is about 15 minutes. That's a "circle" that is 1.5 miles across, which is a an area of about 1132 acres (Ignore that straight roads don't have circles; pretend the "extra" area is support stuff, shops, whatever). 1132 acres of single family housing is 13,000 houses if "close", upwards of 20,000 units if we go to townhomes/rowhouses.
13k dwelling units all within a 3/4 mile walk from the edge; that should support at least one bus.
Well, one could make an on-demand share taxi/microbus service that serves between those cul-de-sacs and the closest avenue that is served by full size fixed-route scheduled buses.
Walking with the dogs the approx 400' to the nearest cul-de-sac is a harrowing affair. Bike riding is so intimidating that my bike hasn't even gone outside in months. Yeah people ride on it but it's way outside my comfort zone.
Pretty much all of suburbia needs to be magically terraformed, for any of these things to be feasible.
> If you're wanting to haul things like pets and lumber, recent cargo e-bikes can haul a lot.
I don't think you realize how big a 3/4 x 48 x 96 is. I can't even fit it in my Forester without ripping it lengthwise and driving with the hatch propped.