Starlink uses wireless connections, be them laser or radio. That just cannot scale in the same way that fiber can. It's an apples and oranges comparison.
Quick note that: yes, but free space laser is a bit different than wireless because bandwidth can be extremely high and adjacent transmitter interference is essentially zero.
Couldn't you scale horizontally, e.g. with thousands of satellite base stations scattered across a continent? Then each one could occupy a separate, non-overlapping spatial channel.
Perhaps you could split up and distribute your network backbone over something like that?
That'd require scaling up either the number of satellites or their size (talking to thousands of base stations at once = more power, more antennae) dramatically.
It is possible with micromirror devices to have a single lens on a satellite to send thousands of beams in different directions.
That opens up the idea of N satellites having N^2 bandwidth... Which scales much better than optical fibers, where in general to have double the amount of bandwidth, you have double the cable laying effort.
Current starlink satellites do not have this ability - they can connect to max 3 other satellites I believe, which is pretty much the minimum for a fully connected network.
Because the "beam" in a fiber is tiny and can be controlled, while the beam between two sats is actually very large and runs in free space. Most of the transmitted energy will always overshoot the receiver, resulting in significant crosstalk issues once multiple sats are in sight of each other. You cannot have two beams running the same path on the same frequency, not in space. But new fiber can be laid down infinitely along identical paths without any degradation.
Until you put all of Sweden (and the people they want to talk to, like Estonia) in space, that data's going to have to come down at some point. Fast inter-satellite data doesn't help you if it has to queue to get in/out of space.
Both are expensive, for sure, but the undersea cables will be used and paid for by major internet providers, whereas finding customers for Starlink is still proving to be tricky.