I often see that around certain countries, the number of waypoints shown on IF are abundant whereas around certain regions of the globe they are sparsely available.
(Not considering the waypoints near airports)
a) Is this phenomenon same as in real life?
b) Why is this uneven distribution present in IF/real life? And on what basis are waypoints plotted?
Some airspaces are busier than others. You’re going to find many more waypoints in Los Angeles (lots of airports in a small area) than you will in Edmonton. Some waypoints are “aligned” with runways so you can make your flight plan lead exactly to the runway. Others are made at certain longitudes and latitudes. You’re likely to find these over the Atlantic Ocean. So waypoints are intentionally dispersed unevenly.