My residence hall (we don't really say "dorm" in the UK any more) had these "expensive" things to hold the doors open, back in the early 2000s. It's an electromagnet connected to the fire alarm system; the door has a metal plate.

This is a safety improvement, because it avoids people propping doors open with wedges, chairs or fire extinguishers.

All the halls had them, as well as many doors in the academic buildings, whether they were new buildings or renovated 19th century buildings.