Light pollution from satellite swarms is an economic externality. Any company can dump sewage in the river (and maybe the sewage is necessary for progress!) but the private sector profits by consuming a shared resource.
For the night sky and astronomy the externality is not so great in the grand scheme, but if unmitigated it does mean that there will be fewer discoveries per taxpayer dollar sent to the NSF/NASA. I'm a postdoc in astronomy and am all aboard Starlink-style networking. But it also seems fair to me that SpaceX should be the party that's responsible for treating that externality with light pollution, or else it's the same old "privatize the gains and socialize the cleanup." We've already effectively achieved this for radio astronomy by regulating protected bands in the spectrum for passive listening.
For the night sky and astronomy the externality is not so great in the grand scheme, but if unmitigated it does mean that there will be fewer discoveries per taxpayer dollar sent to the NSF/NASA. I'm a postdoc in astronomy and am all aboard Starlink-style networking. But it also seems fair to me that SpaceX should be the party that's responsible for treating that externality with light pollution, or else it's the same old "privatize the gains and socialize the cleanup." We've already effectively achieved this for radio astronomy by regulating protected bands in the spectrum for passive listening.