Some European airlines do allow non company crew and "related professions" to ride on the jump seat, in my experience it has to be people who work at the same base as the airline and is restricted to either positioning airline crew (their own or other companies with a recipricol agreement) or ATCOs who work at that base.
For the ATCOs, it's not a jolly, but almost always a round trip on the same sector, exceptionally a day return, and we're very grateful for the opportunity to remind us what goes on on the other side.