The average user does not have to do anything. Their computer will already be set up in their preferred language and web sites should respect this. The HTML lang tag and hreflang tags further lets developers tell search engines the language of the pages, which search engines use to find the correct page to display. Developers shouldn't try to be smart and force change the language after that. AliExpress is the worst offender of all.
But it gets obnoxious. take your laptop with all the cookies identifying you to a different country? "Oh you must want Google in Swahili!"... Google you must know I don't know Swahili!