It is not clear where they have got their suspicions from unless it is the minutes of the Council's Enterprise Growth and Community Infrastructure Overview and Scrutiny Committee's meeting held on 7 December. In the minutes there is a clarification that 'concessionary fares only applied to ‘standard’ bus services, not for ones with additional services like parking, toilets, etc. The Guided Busway was seen as a ‘standard’ service in this respect, as it could be caught from normal bus stops with no parking or additional services.'
In reality, of course, the Park & Ride services can also be caught from certain ordinary bus stops, and in my experience, if you start your journey from the city centre, you get charged the regular single journey or day ticket price for Cambridge, not the reduced Park & Ride fare. Park & Ride service serve a limited range of bus stops during the day, but after 6.30pm appear to serve all stops on their respective routes, which might seem to imply that they are 'standard' bus services. Information about Park & Ride services, including ticket validity is at this page.
See an earlier blog post for a further comment relating to this topic here.
The Council committee minutes are here .