We cannot expect the private sector to subsidise patients. The National Dental Centre provides for subsidised treatment for patients, but it it reimbursed for the difference in fees by the Government. Private dentists enjoy no such benefit. This makes it comparable to the work done by private practitioners, if you choose to ignore the difference in experience. As with all fees, there is great variance, and some would pay more to see a preferred dentist, while others may choose to seek the cheapest available care.
Dentists are free to set their fees according to their skills and service.