Indeed, I've found it to be quite accurate in my city when zoomed in enough to where the hex grid transitions to green/red dots on individual properties.
In my neighborhood and adjacent communities within a roughly 5-mile radius, utilities are all underground, but the pattern that emerges in these parts when attempting to predict whether a community will have fiber to the home or not appears to be some combination of existing easements/city right-of-way, relative community affluence, and housing density.
For example, AT&T brought fiber to my neighborhood likely because they could easily bury it along the city's right-of-way where not even HOA radicals can stop them. The more affordable townhome community to the immediate west didn't get the same infra though, despite there being comparable townhome communities less than a mile away surrounding a regional park that did. Similarly, the expensive homes within a gated golf country club to the immediate north of us doesn't get fiber despite the affluence living in that community, but the deed restricted community outside the gates to the immediate west which shares the same name did, while the mixed single- and multi-family community to the south of that community didn't. The homes in this area are anywhere between mid-80s to late-90s construction.