The market has already decided that any noise insulation is too much of a cost. That's why there's a bunch of incredibly cheap apartment complexes springing up around Austin with the bare minimum of effort.

And since housing is a zero sum game the market is already rigged in favor of landlords. People generally don't have as much choice where to live when you start considering school access, public transit, commute and so forth. Relying on the market to solve housing will simply result in miniature SFs popping up over the US, just like what's happening to Austin.