In Europe there's also problems with cross-border rail freight, partly due to incompatible systems, and partly due to bureocracy (national operators lobby politicians hard to protect their home turf, while trying to expand internationally, running into the same issue there with the local national operator).

If you look at the share of freight transported by rail as a function of the distance, in the US that curve goes smoothly upwards, as long distances play into the economic benefits of rail, whereas in Europe there's a sharp drop beyond 500-1000km or so. Meaning that international shipments in Europe largely switches to trucks.

If you mean the Betuwelijn, that is apparently still not at full capacity - only 70-80 trains per day instead of the planned 150 or so. Which I guess is still fairly busy by American standards (3-4 TPH now, planned for 6 TPH, averaged across the whole day)

The US is still littered with railroads, and rail carries a large amount of cargo.

It's still not not as dense as UK, Germany, or Netherlands, and cannot be, outside areas like North-East. What makes sense around places like NYC, Chicago, or Seattle, may not work equally well in Nebraska. Building a road and running trucks on it is just more affordable.

Also, rail is optimized to have ridiculously high throughput at the expense of latency. Rail is great at hauling grain, huge hunks of steel, wood, etc, but is too slow for time-sensitive stuff like flowers or that birthday present you ordered at a last minute with express delivery.

This is why relatively long-haul trucking exist in the US, despite the presence of a large and busy rail system, to the best of my knowledge.

(Passenger rail vs cars is another kettle of fish entirely.)