The tram train terminus is Network Rail infrastructure, access is through the shopping park and the gates across the road and footpath are all closed and locked by their security after the last tram departs.
SYPTE does have aspirations to buy some neighbouring land to build a bigger park & ride car park, which may change the situation.
Rotherham Parkgate is something of an anomaly - a Network Rail station managed by Stagecoach Supertram and featuring a Northern Rail passenger information system!