Broadcast coverage area, frequency and power are all factors here.
lower bands do not need as much power to carry.

with the digital carrier/modulation, it seems even less power is required for the same coverage area.

i did find a digital vs. analog equivalency chart a couple years ago in my searches.
i'll have to see if i can find it again. City-tv was used as an example.
(likely because they were one of the early broadcasters up and running.)