Green Flag have just changed the way they work. They used to use a network of local garages to cover the country and were paying us £36 for turning out and mileage after 10 miles (hence the reason some of their policies were 10 mile recovery only
)
Recently they accepted the tender of 4/5 larger recovery companies (probably because of the new rate) to cover the whole country. FWIW, that £57 per job will include everything from flat batteries and wheel changes (which i would frequently do 15+ per day) up to the National recovery. £57 for a jump start is good money 
As for the mileage... I can well believe it... One of our trucks had been roung twice when I left
And it drove better faster than any of the others 
We lost our GF contract late last year; we were getting about £40 per call, with mileage if recovered over 15 miles
if the customer had cover - many don't. GF's big attraction used to be the quick response time, which came from using local contractors. As some of my colleagues now work for the London based contractor now covering Kent, Sussex and Surrey, they are expected to go from job to job, no matter where it is. That's a bloody big area to get to inside of an hour! Plus, they 'do' it using small Renault vans with the Rapid Deployment Trailer like the AA use. A big/heavy/automatic car like ours is out of the question. Then you'll be waiting for a truck. Plus, the original driver won't get paid for the job! It's not unusual for drivers to be paid on commission only; now 20% of £57 doesn't look so good for what could take over an hour to do(arriving, doing the job-jump start, wheel change, etc,etc) now does it?
When my original boss sold up 8 years ago, he showed us paperwork(which went in the bin) that the rates hadn't gone up in almost ten years, and they only did
last year! He reckoned that as a small, family owned firm he couldn't afford to keep going, yet we had the local big contracts, and the Police work, where serious money
can be made, but also lost(many jobs don't get paid at all, and many long term ones are only chargeable for once the car is cleared, which is years in some cases).
Mileage? My '10 reg Canter(put on the road 18/12/10) now has over(can't be exact, been on holiday the last two weeks) 53,000miles on it, and it was a quiet year. The tacho exemption was necessary; we'd all regularly done several days on the trot, or had a 500 mile round trip at 3AM after doing a day's work. Those rarely happen now.
Recovery is a right laugh!