[aeroevan]

They mentioned the distortion near the poles when using geohashing (which uses z-order curves), but I doubt they have many users at the North or South Pole.

[biggerfisch]

They seem to have a least a few: https://www.theatlantic.com/technology/archive/2014/02/confi...

[realfun]

not just near the poles. Geohash distortion is already very obvious when you compare UK and countries in south Asia.