My niece wholeheartedly agreed with my frustration. Then she mentioned that her non binary gender roommate would find the horrendous grammar perfectly acceptable. And that’s where I learned something new.
For those of you who aren’t in the know (as I was not), non binary gender is a category for those people who are not exclusively male or female, therefore they have no gender. So in grammar terms, a non binary gender person is at once singular and plural. There is one person, but that person encompasses both female and male. Not only is the singular/plural pronoun admissible here, it’s the right thing to do.
Language is constantly changing. For people who resist change (my hands are waving high), new words and usages can be a constant source of head pounding. But there isn’t much you can do about it except to let go gracefully. There’s mistakes everywhere you look. And who wants to be perfect, right?