My question is exactly what is says in the title.
I've noticed this behavior being common in web-sites and mobile phone applications getting content from the Internet and I do not understand why it is so common. For example, Google Play Store will often use device's language setting for application itself and display all data it gets from the Internet in local language.
Both modern browsers and mobile telephones have language settings. When a browser connects to a web server and requests a page, it will also send a list of acceptable languages together with the request. That list will (by default) at least have on it the language used currently by the browser and users themselves may edit them. Mobile phone applications already know the device's language settings and should be able to send them when connecting to their server. I wouldn't consider it unreasonable to assume that user uses understandable language settings in browser and for the phone's OS.
What I've seen instead is that websites and applications use geolocation to determine the language which they will use when displaying page. While, at the first look, this may not seem a bad idea at the first look, geolocation,especially if combined with inconsiderate* web-site design, will make things very difficult for people who are traveling or who are cursed to have their location incorrectly detected.
So what improvement does geolocation give over just using language settings that device already provides?
P.S. Sorry for the bad title, but I couldn't figure out anything better!
*By inconsiderate I mean gems such as having a language selection menu where names of languages themselves are translated or even incorrect.