Comment by generuso

Modern satellites, in particular Starlink, use optical transceivers that are identical to the ones used for the fiber optic links, with an addition of all the required parts to make them work across free space. So a link between a pair of satellites is very comparable to a single pair of optic fibers.

The cables can go the entire distance between the data centers. The satellites probably connect to their closest neighbors, and any long distance transmission would have to make multiple hops, and share the bandwidth with everything else in the system going through the same nodes.

Since there are hundreds of undersea cables, with a dozen fiber pairs or so each, the cable system has several orders of magnitude greater throughput compared to the current constellation of satellites.