How is their coverage not just a function of latitude in general?

I doubt it. Sure you can deploy mirrors in space to collect and focus light towards PV panels on earth, but the sun isn't any brighter in low earth orbit.

To get meaningful amounts of power you'd need square kilometers of mirrors perfectly positioned. And if you had all that, a single dark cloud could swoop in and block all your incoming power.

But it could be interesting in today's dynamic electricity markets. Solar power plant owners could order some night time sun, if demand and prices surge in their region for whatever reason. I guess it all comes down to SpaceX rideshare pricing and their reflector-tech. Maybe they've got some huge folding or inflating mirrors, which can be deployed by tiny satellites.