On intercity, and long distance rural services circa 1 per carriage is essential.
1-2 per train is fine on outer suburban services.
On Inner-suburban/metro services they are a waste of space.
Every carriage needs to be accessible (i.e. able to accessed) by people with as wide a range of disabilities as possible.
In terms of in-carriage accommodation for people with disabilities, there should be seats close to every doorway on every carriage (for people who are not in wheelchairs but unable to walk a significant distance easily and/or quickly so they can be seated before the train moves and have time to alight without having to stand before the train comes to a halt). On intercity/long distance/outer suburban services there should also be also be 1-2 wheelchair spaces in most carriages (this is not incompatible with my previous comment - just put seats on one side of the train and a wheelchair space opposite). This space must be separate from luggage storage spaces.
On inner suburban/Metro services there should be combined standing/wheelchair areas adjacent to every doorway (with wheelchair priority of course).
A nice to have, but not essential regardless of type of train.
Very significantly useful on outer suburban and longer distance trains. More hassle than they're worth on metro services.
One or two sufficiently large dedicated bike storages area per train is all that is required for outer suburban, inter city and rural services. Inner suburban and metro services should have sufficiently large standing areas that bikes can be accommodated there when not required for standing or wheelchair passengers.
Essential for intercity and long distance rural services. Useful but not essential for suburban routes. Not required for metro carriages.
End of carriage Luggage rack (for larger suitcases)
Essential for intercity services, and long distance rural services. Sometimes useful, sometimes not on outer suburban. A waste of space on inner suburban and metro.
Essential for metro and suburban routes, a nice to have on longer distance routes.
Very nice to have on long-distance intercity and rural routes, especially if there is no buffet. Meh on outer suburban routes. Actively unhelpful on inner suburban and metro.
Onboard Entertainment Screen (NOT requiring Wifi)
Meh on long distance intercity services. A waste of money for everything else.
On intercity routes and anything outer suburban or longer that run infrequently they are essential, but as long as they work whether paper or electronic doesn't really matter.
A big no-no on metro, inner suburban and other high frequency short distance routes.
Onboard information screen (i.e displaying all calling points and the final destination)
See above.
Seats with access to a table.
Essential on intercity and long distance rural - the longer the journeys the more useful a proper table is. For intercity services something like at least 50%-80% of seats should have a proper table. A few proper tables per carriage is fine for outer suburban. Tables are a waste of space on inner suburban and metro routes.
