They have approval for up to 42,000 satellites, most internet connections are shared at homes and businesses, and broadband is over subscribed anyway.
One way to look at it is up to 42 million 4k streams at the same time. But, a significant fraction of the constellation will be over the ocean or other minimally inhabited regions so something like 25% of total bandwidth is likely utilized at any one time. However, that’s spread around the globe with some areas like Hawaii having much better than average available bandwidth.
I don't think there is a treaty about it. These satellites are in space, not in the air. Around 100km usually is used as the boundary or, more practically, as high as your anti-aircraft missiles can go. It does not really make sense to claim everything up in a cone from your country to infinity. Multiple countries claiming different planets at different times would be weird.
SpaceX got approval to launch these satellites from the FCC.
Wasn't some time ago a Chinese satellite blown from their orbit by a missile? I think current technology allows you to blow stuff up from sky quite more then just 100 Km.
Why? Market forces dictate that they should charge _more_ (likely have less competition there; will also be able to provide better service than in densely-populated areas).
One way to look at it is up to 42 million 4k streams at the same time. But, a significant fraction of the constellation will be over the ocean or other minimally inhabited regions so something like 25% of total bandwidth is likely utilized at any one time. However, that’s spread around the globe with some areas like Hawaii having much better than average available bandwidth.