Of course, any demand for improvements will always be the usual mix of NIMBY, people who think almost any government spending is useless, people who don't like change of any sort, people who fear sidewalks will bring in "undesirables", or people who don't seem to understand what an easement is.
It really depends on the neighborhood culture, though. Personally around here (Tampa Florida) I think I've seen more concerns along the lines of "why can't my child safely walk to school". The statistics probably help shed light on the problem too... Florida cities in general has very high pedestrian fatality rates (due to the issue of being a traditional retirement area + poor pedestrian considerations in road design).
I live in a fairly walkable area of the suburbs. I routinely walk to the grocery store, hardware store, restaurants, etc. And yet, the infrastructure kind of sucks. The most direct paths are missing sidewalks in a couple of places. The main road only has a sidewalk on one side for most of it. Many of the intersections have crosswalks on only one, two, or three sides. There are a couple of businesses I almost never visit simply because getting there requires crossing three crosswalks of the same intersection, then doing it again on the way back. And it's a dangerous intersection to cross which requires great care, because people routinely blow through red lights to turn right on red. Naturally, there is zero police enforcement of this.
It even goes beyond a lack of infrastructure and sometimes involves intentional barriers. I used to take a shortcut through the neighborhood next door, which gave me some variety and bypassed one of the bits of missing sidewalk. Then they put up a fence and I can't go that way anymore.
So many places in this country are within a reasonable walking distance of things, but make it unnecessarily difficult to take advantage of that fact. Get rid of pointless fences, put sidewalks and crosswalks everywhere, and you'd improve things significantly.
Sometimes we visit relatives in Atlanta. The mall is literally across the street from where they live. The only legal way to get there is by car. You couldn't even walk to the next crosswalk. It's a mile or two down, and then back up to the mall, but as there is no sidewalk, the police will stop you and ask you why you are walking. Crazy.