The freight companies own the railway, they optimize the rails for freight, which is why we move much more freight by train than Europe. Passenger service is something they do for the federal government subsidy and nothing more.
And actually, sharing tracks between passenger and freight service is something that they don't really do in Europe. Because they share tracks, American passenger trains have to build at a weight on part with freight trains. Most lines in Europe separate out passenger and freight service lines so they can run lighter trains for passenger service.
A big part of why the US moves more by rail is simply because it moves more goods overland than in Europe.
Low latency freight for smaller, high value items is often done on passenger lines (or even passenger trains) because it doesn't put any scheduling pressure on passenger service.
As far as use of freight in Europe, the elephant in the room is that the EU uses a lot more sea freight than the US. Indeed, while the modal split for EU trucking is around 50%, it's around 70% in the US, and it thus seems clear that the real reason that there is less rail shipping within Europe is because there is much more competition from maritime shipping.
This is a perfect example of path-dependent policy. Because the decision was to select for freight, other kinds of rail are "unfeasible". I'm using scare quotes to suggest that it's not really unfeasible, it's a choice.
And since trucking capacity has been maxed out in the US for quite a while (Amazon is the big mover for this situation, even before covid), you can bet this path dependence is biting us now.
And actually, sharing tracks between passenger and freight service is something that they don't really do in Europe. Because they share tracks, American passenger trains have to build at a weight on part with freight trains. Most lines in Europe separate out passenger and freight service lines so they can run lighter trains for passenger service.