An operator such as Hospidea clearly has commercial motivations, but they will have a contract with the hospital trust and it's those legal provisions that will contain certain allowances. One common model was that operators cover all the costs of the equipment install & maintenance, and in return prices were capped at a certain level - which may well be the figures you're seeing. Ofcom, the telecoms regulator, would require that call costs are clearly notified, but beyond that consumer choice takes over and individual users can decide whether to use that service or not.
Hospital mobile coverage is currently a hot topic, alongside in-building mobile coverage in general. Many trusts now have dedicated internal coverage systems with one or multiple mobile operators, others take the view that mobile networks have responsibility for coverage while they provide indoor WiFi instead.
If a particular hospital trust appears to take the view that provision of expensive bedside phones alongside WiFi, is a way of mitigating for poor indoor mobile coverage, then you may wish to take that up with the trust directly. Alongside using WiFi-calling to provide your own internal mobile service.
