how so? stock markets are using lasers to reduce trading latency vs everything else available so what do you mean not usable for real time communication?
There's an inherent limit to how fast you can communicate with objects in space, so a video call with someone where you will have 1-2s of lag (guaranteed by laws of physics, not occasionally) might be unusable. There is also the impact of distance, you might have even higher latency to the same object depending on the time of the year (Earth - Mars today vs Earth - Mars few months out).
Your figures are totally wrong. The distance to geostationary orbit is around 30,000 km, so at the speed of light (~300,000 km/s), that is 100 ms of latency.
Low earth orbit is 3,000 km or so, meaning that's only 10 ms each way.
Odds are good that if you had a mesh network of low earth orbit satellites (like Starlink) you could actually get an antipodal point-to-point video call with less latency than with terrestrial fiber. That's not a function of bad terrestrial switching/routing: it's the fact that light travels faster through vacuum.
