Freeview viewers are limited in the number of choices they've got simply because of the limited availability of frequencies within the radio spectrum.
With ever-growing numbers of devices requiring radio frequencies allocated for their sole use (e.g. 4G phones, 5G phones, wireless headphones, wifi devices, Bluetooth devices, satellite TV, etc), as well as long-established users (such as radio broadcasters, emergency services, taxi firms, etc), there's only a very tiny part of the radio spectrum available for use by terrestrial broadcasters and they have to decide how they'll use it.
For those reasons, there have always been fewer BBC Red Button services available to Freeview users than to viewers using other platforms but the number was further reduced back in 2009 when the BBC removed some of the Red Button feeds in order to provide space for new BBC HD channels.