Happens frequently in private.
GPs and specialists over charging or choosing more expensive treatments to line their wallets.
Just saw another patient yesterday who was following up with a specialist (not Ortho / endocrine) for an unrelated issue, who has been on IV bisphosphonates costing 1000+ dollars a year, and she had no idea there was an oral alternative which prolly cost 10% of the cost. And she has no contraindication to oral bisphosphonates.

Another patient I had was given a customised combination steroid / moisturizer / antibiotic cream from private derm which was $300+, when the same individual creams can prolly be bought at $50 tops.

Most of the time it’s willing buyer, willing seller.
But the problem is that many patients are not even made aware of the alternatives.