Technology

I mean, zoning is kind of the smallest hurdle for a rural town.

Yeah, that's why it's essential to do first.

Developing public transit and construction to make streets bike friendly are significantly larger investments.

Car traffic is the only thing making streets bike unfriendly in the first place. Fix that, and you don't need bike lanes and whatnot.

Besides, this argument gets its order of operations backwards. You've got to quit massively subsidizing driving first in order to get people out of their cars and justify the investment in transit.

And for colonial era towns, construction is often not an option because of the likelihood that something has historical significance.

Colonial era towns are often the least problematic to begin with. It's the towns that have been demolished to accommodate cars that suck. In fact, I'd wager that any parking lots that do exist in colonial era towns are very likely to occupy space that would've been historically significant if it weren't already lost.