Satellite systems have extremely limited bandwidth capabilities compared to terrestrial systems. The difference with Starlink and similar systems being developed now is that they are in low- or medium-earth orbits not geostationary, and consist of hundreds or thousands of satellites, and not one. Therefore the total customer base that can be serviced can be scaled with the number of satellites.
But it’s still limited by the laws of physics, the power capability of each satellite, and total spectrum allocation for the satellite to ground leg. Starlink has 250 MHz of spectrum for their transmit and receive channels at 11.2 and 12.2 GHz. There is only so much data that can be pumped through that.
The total capacity of even LEO satellite systems are probably a tiny fraction of the capacity of the terrestrial mobile network, which is turn only has about 10% the capacity of the fixed network (NBN, etc). A growing amount of international traffic goes on submarine optical fibres these days, simply due to their much larger capacity, along with much lower latency than traditional geostationary satellite systems.
Starlink uses LEO satellites at 550 km altitude, so the roundtrip airgap latency on Starlink is about 4ms. This does not include processing delays in coding and decoding transmitted and received data packets, and forwarding them to their destination.
