Norway 🇳🇴
Very easy. You will probably have the Entur app on your phone, for checking train times, bus times, viewing your seat reservations (although not for buying seat reservations. You have to do that on their website).
They also sell local tickets. You need to select the local public transport authority - for example Ruter for Oslo, Skyss for Bergen - and then you can buy single or day tickets with your saved credit card.
Example prices:
Oslo Zone 1 - 44 NOK for 1 hour, 132 NOK for 24h, 366 NOK for a week. (This is good enough for trams, buses, ferries, T-bane (metro) for most of the city centre, and the nearest islands, but not to Bygdøy).
