Is the total possible bandwidth available on these even comparable to optical fibers?
Comcast is generally in the 20-30 neighborhood, unless you are using their gigabit service, then it is more like 10-15 milliseconds.
So it is higher, but not debilitatingly so (unless your application is very sensitive to latency). I would imagine there is a lot more jitter in Starlink, but that is more a feel than real numbers.
Mainly on a terrestrial system you wind up bouncing through more substations on the way to the general Internet, whereas with Starlink you are generally bouncing straight from your dish to the satellite to the base station. So less bounces, but farther to go. The physics favors the wire, but not as much as it used to.