And those people would be misinterpreting evidence based on church windows and do not take into consideration antique telescopic lenses which would have lost all their clarity if glass did indeed flow.
The Victorian church window thing is likely wrong considering that ancient Egyptian glass figurines aren't puddles on the floor, but it still doesn't rule out the possibility that glass flows at an even slower imperceptible rate.
The question whether glass is truly a liquid or not is a matter still in debate in academic circles (some have even gone so far as to classify glass as a fourth state of matter which sits between solid and liquid).
However it is not doubted that glass's molecular structure is loosely connected similar to liquid, and that we see through it because of the gaps between atoms.