What I find bizarre is that NIR and Ulsterbus use PlusBus in Northern Ireland - even though NIR isn't a ATOC member and even though Translink own both services. NIR and Ulsterbus even print their tickets on the same ticket stock. I've no idea why they must be paying to use the PlusBus branding and service when they could surely offer the same kind of rail and bus tickets themselves.
http://www.translink.co.uk/NI-Railways/Footer/PlusBus/
I've never understood why Translink couldn't get their act together and allow through tickets to be bought for combinations of trains and buses given that they are in a fairly unique situation of being one company controlling both.