Those would seem to be the most important people to understand why they think transit isn't fitting their needs. It could be that (1) they are wrong and just don't understand the system, or (2) the local transit system actually fails them (doesn't serve close enough, often enough, safe enough, direct enough, late enough, etc.) in a way that can be improved.
Survata co-founder here. The first graph does not include those respondents. As the footnote says, "Respondents who answered that they 'never' use public transportation were excluded."