I can assure you that a plusbus ticket is one that a driver will not see very often.
Last year my wife and I visited Glasgow and bought PlusBus tickets.
We boarded 5 buses throughout the day and on EVERY ONE, the driver initially said we couldn't use the ticket. After explaining what they were, we were able to board.
I just assumed the PlusBus scheme must have been pretty new, meaning the drivers were not aware of it.I even emailed PluisBus with my thoughts, since many a user being told no would simply accept the fact and end up paying for a ticket
To my surprise, the scheme is not new at all .. it actually started in 2002.
Maybe it just isn't well advertised.
We love it .. we were in Edinburgh a few weeks ago and the PlusBus ticket can be used on all buses as well as the trams (excluding the one stop at the airport)