I think there are a lot of myths in Pakistan on glass coating.
If you ever need to repaint the panel, they painter will scrubb the paint off first, so the glass coating is actually getting scrubbed off with the paint. I guess its name (glass coating) confuses a lot of people, and thats why a lot of companies have started calling it either quartz coat, ceramic coat etc etc...
It isnt glass at the end of the day, more like a thin layer of extra clear coat sitting on top of existing clear coat. It does exactly what clear coat does, prevent scratches, airborne chemicals and insects etc from penetrating or bonding with the painted surface.
Yes, it is true that at the end of the day, removing the glass coating will require compounding to get rid of it completely, which will basically eat some of the clear coat/coating, however, it is not as difficult as people seem to believe.
Most importantly, preparation is really important before coating any car, as whatever sits on the paint currently will sit under the coat as well and will always be visible.
I hope it makes sense.