FB group reminded me of something I had forgotten about:
It could be (i have no proof) that
Tello adjusts its wifi channels and possibly throttles wifi power according to regional settings to keep the legal limits.
I know that Parrot does exactly this with their Bebop.
I never looked closely how
Tello handles this, but I have seen references to regional codes somewhere.
To check that we'd need someone with a test rig to see if there is in fact a difference in transmission power. Just doing some field tests doesn't really cut and is not worth the effort.
Is there someone on the forum with the equipment and know-how willing to check if there is indeed a difference?