[Just a conjecture]
The western notes are different from the eastern.
Speaking in C-major-centric terms, a just-intoned Ab is 8/5, G# is 25/16. This is a difference of more than 1/3 semitone.
On an equal-tempered keyboard that note is half-way between ie 800 cents.

My conjecture is that the western ear not being familiar with any minor-sixth other than 800 cents hears it as such.
The eastern ear auto-corrects it up to the just-intoned 8/5.

I have been often mystified by the contradiction:
Western theory insists on the distinction between G# and Ab (augmented fifth and minor sixth). And then makes them into the same note

The eastern ear easily hears the difference and yet the theory (I am speaking for Indian) does not allow the notes to exist!  To an Indian music theoretician tivra-pa (G# or augmented fifth) is a contradiction in terms because pa (fifth, sol) is achala -- unchangeable.