The whole thing is a joke. The intention was all PTE products - Saveaway, Solo,Trio and Railpass could be loaded onto the ITSO cards. Near 10 years later and its only recently become possible to load the Railpass onto them. Trio still not available. Solo was to be rolled out on them to topup onboard buses, around 4 years ago this was rolled out for one morning, due to a technical issue was axed the same day, and never came back since. Paper issue one day Solo (bus only) is available onboard buses. Other periods are available at paypoint and bus stations.
Considering in Manchester the system 1 day passes for bus tram train can be sold on a bus, tram etc shows how easy it is to do, but Merseytravel just seem incapable.
GMs "igo" card for ID for child fare is a brilliant scheme too and works well from my experience, unlike Merseytravel who dont care about revenue lost from sale of Child fare passes to any age.