I use a different payment provider and pay 2% of the transaction as the processing fee and renting a portable terminal is £349 each per year. I imagine a longstanding business like OUFC pays between 1.5% assuming our ticket office is operating independently in terms of administration. Most basic modern terminals probably cost between £20-40 to rent a month these days. I know Ticketmaster has their cuts and fees but I don't know if that extends to supplying the payment framework on top with the provider. Either way, OUFC are losing small money on the face value of a ticket but it probably works out cheaper than if we did it in-house and had to pay for a weekly collection plus it takes less staff to facilitate.
The scary thing going forward is that physical ticket offices may also become a thing of the past. It very well may turn into online only in time with top up cards acting as personal match tickets and season tickets as well as the print options. I remember when we moved to the Kassam and you'd have the windows stacked and the phones buzzing but if we did move to the new home then I'd expect a very scaled-back operation. Ticketmaster were once untouchable and virtually printing money in this domain but things are changing with the times.