Do all schools have candidates at tenure-track campus interviews meet extensively with faculty members and administrators one-on-one? Are there schools where it is customary to devote a campus visit primarily to group interviews (faculty and students), job talk and/or sample class, tours of the facilities, and meals (with faculty)? Basically, does such a schedule signal lack of interest or is that the usual in some places?
Whatever the schedule is, it's almost certainly identical for all candidates. You can't deduce anything about the school's interest from the schedule.
The way my department does tenure-track interviews, the only one-on-one meetings are with the department chair and the dean. Other than that, there are, as in your description, group interviews with faculty and students, a research talk, a sample class, and meals with a group of faculty. The schedule doesn't include one-on-one meetings with individual faculty. And this is the same for all candidates.
(This is a mathematical sciences department at a medium-sized public university in the US.)
Also take into consideration their overall interviewing load. If it is a large department and they are interviewing many candidates for a position or especially have many positions to fill, it may be extremely difficult to manage 1-on-1 interviews and keep everybody's sanity.
While a lack of scheduled 1-on-1 interviews could indicate a lack of interest, it generally is just a function of how the search, and possibly other searches, is being run. For example, my current department does not use 1-on-1 interviews as part of the formal hiring process since HR mandates that the same formal process is used for all campus visits. We have to ask identical questions to all the candidates at the panel interview. That said, almost every candidate we interview, and from what I remember every candidate we have hired, has asked to meet with a small number of faculty members (generally within our department, but sometimes outside our department) individually. If the visit does not include meetings with the people you would be interested in collaborating/interacting with, then you need to ask the search committee to arrange meetings.