There are more rail companies in Europe, than in US. If you bothered looking at the UK, you'd notice that they alone has as many freight companies at US.

In US rail companies aren't exactly known for innovation either, because of extreme distances they haul and already efficient diesel-electric locomotives - there's no practical pressures to innovate at all.

There are multiple reasons why rail traffic in Europe and US is different, but none of it is because "socialism".