This is because these are 3 hubs of jobs and places that people want to be but are also unlikely to have cars at because students are broke, people in downtowns don't need cars, and travellers by plane lack cars as well fod obvious reasons.

This is why transit systems like the Cincinnati Streetcar fail as while it meets the downtowns needs, it f ails to provide real connections, if it were to be extended to UC then it would be a much more functional transport system as it would give mobility to people instead of acting as a people mover

please dont forget hospitals for a lot of disabled ppl public transit is the only option for transport and we're always in and out of hospitals & only have a certain allowance in our benefits for ambulances and they absolutely track why we use it