"It costs an AVERAGE of £20-£30 every time they deal with the public face-to-face?
Anyone else think this is through the roof?"
Depends - that cost per transaction wont simply be the 'hourly rate' of the staff member involved. Total staffing costs will include loadings for infrastructure (the cost of the building, heating, insurance etc etc).
Also we dont know how long average transactions are - certainly any time I have had to queue for a F2F at council offices, people in front of me seem to take an inordinate time.
Other people are hell..............