Do satellite networks not move the needle in terms of capacity/reliability now?

Conceptually, it's the difference between your wifi versus running a single fiber to each room in your house. The difference in bandwidth is multiple orders of magnitude.

This is never going to change because from a physical perspective free radio is a shared medium while each individual fiber (or wire) has its own private bandwidth.

Only a little bit. Just clicking around, a new Hawaii cable is supposed to have 24 Fiber Pairs and 18Tbit per Fiber Pair at the end of this year. If you lose several tbits of bandwidth, you're going to have a hard time making it up with satellite.

For small island countries and such, satellite capacity may be sufficient; and it is likely helpful for keeping international calling alive even if it's not sufficient for international data. But when you drop capacity by a factor of 1000, it's going to be super messy.

No. They're not setup to be a principal route between two nations and most satellite networks until very recently didn't even route messages through other satellites but instead retransmitted them to a ground station with access to hardline internet. Even Starlink mostly does this still because it's way cheaper and easier.

I never understand why questions like this get downvoted around here.