Because things, unfortunately, cost money to run. Digital crowdsourcing isn't magic, it requires adequate infrastructure to run and facilitate said crowdsourcing data.

Static maps are easy, load em up on a server and people just download one way. Sure it might get a little slow when busy but eh.

Live things however require constant near-real-time communication to be useful. And that requires servers and bandwidth and other infrastructure.

And that's not even going into how the premium fee goes back into further development and refinement of other features and maintenance.

And before you say "Well, federation!" I say well look at the Threadiverse, each is comprised of individual instances that's true. But each instance, has a bill they have to pay to keep running.