It's very dependent on which region, which route and which train company you're travelling with.

From a Yorkshire perspective, if your train runs North-South through bigger cities i.e. Edinburgh, Newcastle, York, Leeds, The South etc, without stopping at small in-between stations, you get 100 people on a 10 carriage long futuristic aerodynamic LNER Azuma Class 800 train, that feels like a luxury private jet and travels at 125mph.

If your train travels East-West and stops at places like Halifax, Bradford, Wakefield, Selby, Hull, but also stops at little in-between stations called stuff like Boggy Fence, Coaltown, Upper Frogbottom, Chough, Milton-upon-Jeremy and Thribblewick, you get 400 people squashed onto a 2 carriage Northern Rail Sprinter, that feels like a livestock wagon and travels at 30mph. It's perfectly pleasant outside of commuter times, to be fair.

When the train is stopping at stations 5 miles apart, there's not a lot of room for big fancy trains to do big fancy train things like "accelerate smoothly and aerodynamically" and "brake gently and quietly like a falling leaf".

The Class 800 may have seats made from cardboard, but they do at least look like they were designed this century.