It does, though, because long-distance travellers need comfort, high luggage space and catering, but short-distance commuters need as much capacity as possible.
Is this really the case or are you stating it as if it were a fact? In any case I suggest that the premise is false.
The term 'commuter' is a borrowed Americanism which referred to ticket prices being 'commuted' or reduced to a less severe level. In the UK such people used to be called 'season ticket holders'.
Not all short distance passengers are season ticket holders[1] travelling only with a brief case, newspaper, umbrella and bowler hat; some season ticket holders may be carrying luggage in the sense of rucksacks, bags, cases or bicycles. Short distance passengers may be occasional travellers and be travelling for a variety of reasons and carrying, or not carrying, items of luggage such as bicycles or baby buggies.
Not all long distance passengers are carrying luggage or need or want to eat or drink. Some may be doing it regularly several times a week[1].
It maybe that the exposure to the world of computer software (as is the case for many people posting here) has resulted in them seeing the world as binary - it's on or off. You are for us or against us. But the world at a human level is not binary, it is analogue. There is a continuous spectrum of situations, desires, needs and answers.
Pigeon holing all these things under one of two headings means that not only will neither of the groups you identify be properly satisfied but also all those who fall outside these definitions will be ignored completely.
[1] Although some may be travelling between, for example, Chippenham[2] and London which I do not consider to be, in UK terms, short distance.
[2] Chippenham is in an odd position. I understand that roughly equal numbers of people travel west to Bath and Bristol in the morning peak as travel east to Swindon, Reading and London. What would be the most suitable service for a place such as this? An 'Inter-City' service or a 'commuter service'?
Combining them results in inefficiency and poor compromise - for instance, running an 11-coach train all the way from London to Scotland just to provide for London-MK passengers, and you have reduced comfort so you can cram those passengers in.
Combined use of this kind just results in the worst of both worlds - like Switzerland's awful IC2000 Dosto stock with no legroom and narrow seats.
56 minutes is probably long enough to be a long distance journey, to be fair to you. However, most of those heavy commuter loads under discussion for the UK aren't. Euston-MK and Paddington-Reading are both about half an hour. Coventry-Brum is even less than that. These are precisely the journeys that should be on local trains.