It’s because it doesn’t really make sense to plot the results of random() in a circle like this. There’s the same number of points with radius between 0 and 1/2

It’s because it doesn’t really make sense to plot the results of random() in a circle like this. There’s the same number of points with radius between 0 and 1/2 as between 1/2 and 1, but they have to fit in a space with 1/3 the area as the outer band. So it’s naturally more dense. The fact that random(random()) /looks/ more even in this visualization shows that the actual distribution is not.