Individual perceptions of reality are not necessarily representative of the collective perception of reality from millions/billions of people interacting with the same physical environment. The collective perception, where it is agreement, is a far more compelling baseline.
Perception, individual and/or shared, is just an impression of whatever it is that is communicating with the senses and soul/consciousness.
If you smell something, for example, there is certainly something happening somewhere within your neural architecture that corresponds with that experience. It could be due to an actual odor affecting your taste/smell buds or it could be imagined, but either way there is some corresponding neural event or else you would not experience the perception of the scent.
We use the senses to ascertain what we can about realities beyond our senses, just as we use social communication to corroborate things we perceive in order to gain more data regarding what we perceive.
Sadly, humans are capable of lies, misperceptions, misinterpretations, etc. and then they also argue of the existence of abstract realities beyond what's directly accessible by means of sensory perception.
Despite all the intricacies of perception and reality, there remains the possibility of true and false perception, analysis, extrapolation, interpolation, inference, etc.
And yet because of this possibility of getting things right and wrong, there also remains the possibility of power struggles in which truth claims and accusations of falsity are undertaken for various reason in various ways and according to different interests.