All NHS prescription drugs are free in the UK. Some people have to pay prescription fee (currently £9.35 per item) but diabetics get an exemption for that too (for all NHS prescriptions).
The price you see is the cost to the NHS, not the patient.
Indeed, and I think it's important to show those prices because otherwise you'll find people saying "It's not free you still have to pay loads through taxes".
So I find it best to ignore that and show them that the whole system is still only paying a tiny fraction of what they're paying.
Central NHS negotiations for the whole country also saves a lot of money by reducing expenses related to insurance, administration, pharmacy benefit managers etc.
On the other hand, it may take away some choice people have in selecting health care provider. For example, some people are not happy that they don't get semaglutide (which really helps diabetics to lose weight) because they don't qualify according to the NHS criteria (not obese enough). Of course, they always have a chance to go to private health care providers and pay full price (or private insurance) but not many can afford that. Although I suspect that even in the US many insurers will have similar criteria whether they reimburse the drug or not.
The price you see is the cost to the NHS, not the patient.