[mdoar]

What about the locale of the user producing a different sort order?

[cldellow]

They do specify that it's for sorting numbers, as opposed to say, text. Do some locales sort numbers differently?

[nacs]

They could interpret the input data differently.

For example, a decimal mark difference[1] between locales (like comma instead of a period in floating point numbers) could yield bad results.

[1] https://en.wikipedia.org/wiki/Decimal_mark