Rolling a die isn't truly random either. Given the same environmental conditions and the same force vectors, you will always get the same result.
I think their definition of true randomness is flawed. It does not matter whether it's truly random, rather it should about whether it's random to a point where it's out of the operator's control and ability to predict.
Given absolutely identical conditions, yes. Ignoring quantum effects. But rolling a die is definitely in the realm of chaotic behavior, especially when any reasonable force is applied, so extremely minor changes cause massive, unpredictable end results.
In practice, such precise conditions are completely impossible, and the end result is unpredictable as long as it tumbles enough times. Shake it around in a cup to randomize the starting location, and you're as good as you can get.
I think their definition of true randomness is flawed. It does not matter whether it's truly random, rather it should about whether it's random to a point where it's out of the operator's control and ability to predict.