I would use the Metrolink more often (I live close to the East Didsbury line) if I was allowed to use it with my £1100 p.a. System One Countycard, which gives me all buses and trains in Gt. Manchester but not Metrolink!!!
At the risk of turning this into a public transport forum, we have the same daft situation in Nottingham where you can't have one monthly, or contactless payment card for all operators (tram, rail and bus), because of the daft competition rules that HMG (not Europe) has made. It makes a total nonsense of an "integrated Transport System", which is in part why our roads are so congested.