I find a few eating places on the motor way charge you for a slice of toast that could buy a loaf of bread , how they get away with this I have no idea
The harsh reality of a commercial world is, it's called supply and demand, Patsy. Particularly on the motorway, there is usually more than one eatery to choose from.
Service station eating is always going to be contentious in all sorts of ways. Sometimes a picnic/tapas is the answer.
When I left over 10 years ago the profit on between 40 and 60 thousand litres of fuel was about £1000.