Why quicksort is more popular than radix-sort?

Question

Why quicksort(or introsort), or any comparison-based sorting algorithm is more common than radix-sort? Especially for sorting numbers.

Radix-sort is not comparison b

Answer 1

Radix sort is slower for (most) real world use cases.

One reason is the complexity of the algorithm:

If items are unique, k >= log(n). Even with duplicate items, the set of problems where k < log(n) is small.

Another is the implementation:

The additional memory requirement (which in it self is a disadvantage), affects cache performance negatively.

I think it is safe to say that many libraries, like the standard library, use Quicksort because it performs better in the majority of cases. I don't think that "difficult implementation" or "less intuitive" are major factors.