I was having this same conversation with a colleague the other day. I think the vacancies (jobs) in the US are often standardized by the organization. I have worked in places where HR would write all job descriptions. I haven’t seen that in some time, but imagine it still happens. I have worked in places where the UX team copied and pasted from other job descriptions available on the web to create “their own.” But if the job description is truly based on the work to be completed, then it is not the root cause of the problem — only a contributor. If many of the UX positions are truly the same positions, then it would make sense for the position description to follow suit.
We are humans and like other primates, we learn by watching and mimicking. I think what we are seeing is a monkey see, monkey do behavior in the midst of the explosive popularity of UX.