A good example of catering, was, after three successive companies went bust, on a "short term" basis, one train company went 'self employed'. Basically, the stuff was bought from a supplier & management company, the staff got no wages, just a uniform.
A prepacked Kenco cup of tea, coffee or hot chocolate was bought for £0.66 and sold for £1. (ie supplier 66%, concessionaire 34%)
Most items on the trolley were 34% except Sandwiches, 50% - as these are often unsold & wasted.
In some weeks, staff would take £900, and keep £300. In some weeks, staff would take £1800, and keep £600.
Unsurprisingly, this was the most successful catering operation the railway had ever known. Keen staff, flying through the train, almost zero sickness, every train covered, no shortage of applicants.
Now, 25 years later, that wouldn't happen. Unfortunately, with all the RailGourmets etc ...vulture firms wanting to take a cut pushing coffee to £3.50, catering will never be profitable. But this proves a point - the cheap £1 coffee will sell, if advertised well.
Other than settling for vending machines - the train company should directly employ the staff, manage them well to ensure high coverage and other than booze, resist the temptation to sell luxury junk - just cheapo Kenco(ish) coffee for £1. Those instant £1 coffees will sell out and make far more profit than seen on one current (failed) intercity company, not unknown to sell just three cups of not "Starbucks" at £3.40 a tepid cup - on a busy 250 seat five-car train.
