Please do not confuse uniform randomness with randomness at all.

On your die, if you colour one face in black and the other 5 faces in black, rolling it will still produce a random outcome. It's just that you get a 1:5 skew.

Or look at the probability that a given C-14 carbon isotope will decay tomorrow. As far as we can tell, that's as random as it physically gets. With the die you could theoretically try to run a physics simulation to predict how it rolls, but as far as we can tell, atomic decay is intrinsically random.

However a C-14 atom has about 1 in 3 million chance to decay on any given day.