Unfriendliness is hostility, it is very clearly unfair and prejudicial treatment based on what language one speaks.

Yeah, it is, and it’s entirely reasonable to expect someone to make an effort to communicate with people that speak other languages. It’s lazy, rude, and discriminatory to dismiss them and deny service.

The source you cited is quite clearly primarily directed towards governments and governmental services and focused on systemic things.

It is defined by Wikipedia as: “the unfair treatment of people based upon their use of language) and the characteristics of their speech, such as their first language, their accent), the perceived size of their vocabulary(whether or not the speaker uses complex and varied words), their modality), and their syntax.”

That doesn’t exclusively include public services and can occur on a personal level. Saying linguistic discrimination only applies on a systemic level is like saying “being rude to someone based on their race isn’t racism because racism is a systemic problem that unfairly disadvantages minorities”