I think the problem with fiber in general is not availability, but deployment cost. You need to dig and bury the fiber. That's expensive.

The deployment cost is even lower when you don’t need to put a tower on the ground, which is the point of this. They can cover the entire U.S. to eliminate coverage gaps using the starlink satellites.

You could mount it on poles.

For remote areas that might still be tens to hundreds of kilometers of poles and fiber just to add coverage to one remote area. Then you move on to the next.

No one wants to do that across all of Alaska or the Australian outback.

We have cellular issues in upstate NY that has plenty of infrastructure. Dark fiber is also practically everywhere

Sure, but there's also cellular issues in the Australian outback and most of Alaska, and there you don't have infrastructure.

You need power as well as fiber.

In the sense "you can buy fiber cheaply by the ton", not. But in the sense "laying down fiber in the mountains of Papua-New Guinea, or in the Canadian Arctic, or a simmering warzone full of militias", that is indeed a major bottleneck.

So, location-dependent.

It's absolutely the bottleneck in some remote areas, and satellite backhaul for terrestrial mobile networks has been a thing before Starlink, as far as I know.

It is outside of cities.