>>1997361>ramps everywhere inside the trainsThat's because of accessibility regulations. Corail coaches are high floor, so they don't have that problem, but they make accessibility for wheelchairs (and prams for that matter) very difficult.
However I think trains should simply be mostly high-floor, with just one or two coaches with a low floor section. It would make for a more comfortable interior design, and likely be cheaper too, since you get a lot more space for the mechanical components.