Nope they can’t is the short answer, only try!
It might be a cost cutting exercise, But I suspect ease and training of the nurses is playing a bigger role in this decision...
There will be diabetic patients who are daily visited by the district nurse, who will be taking BG’s and injecting insulin for patients unable to do these themselves... These patients are in their own home, or residential care
District Nurses, are renowned for not having a glue about various meters or how to use them , so they have to been trained for each meter available, some practices try to get all their patients on the same meter, so that all staff know how to work that one individual meter!
Also some surgeries will invest in the meter software, if everybody is using the same meters, then they only need one software program... Get’s expensive if they have to buy several different program..
But you do have a choice of meters, and the surgery can’t enforce you to comply, as different meters are suitable for different people, as individual ease of use, eyesight and dexterity of the user will mean one meter is better than another..