One of the number one reasons for track closures (at least here in Germany) is “unauthorised personal on the tracks”. They then often keep it closed for hours until federal police has checked the complete area.

So no it doesn’t need to be the same train to be annoying.

… European train tracks are usually dual use and highly frequented. Freight trains have to guarantee a certain minimum velocity (80km/h in a lot of areas by now, rarely below 60km/h)

And trains are not simply stopped somewhere usually, but run from freight yard to freight yard. These are camera controlled, including ingress and egress routes. Additionally on some routes there are camera controls and neuralgic points and train tracks these days are often monitored by IR capable helicopters/drones these days. And of course due to higher population density the general chance of someone seeing the “passenger” on the train is much much higher.

So the chance that someone sees the unwanted passenger is much higher. In the very best scenario the person gets caught before the train leaves the yard. This will still be a felony in almost all jurisdictions and a civil lawsuit for the damages the delay caused. (Around 20k € at least). At least it’s “only” the freight customers and the train crews who suffer.

In a less optimal scenario the person is seen on the train. This means the train will be stopped at a station where police waits (often with a helicopter or drone ready these days…hybrid warfare has made people uneasy) and tracks will be shut down. This time not only the people mentioned before suffer but often also hundreds of train passengers. Because this will cause delays,even when it happens at night.

In the worst scenario the whole thing goes wrong. I personally had the displeasure of working with the aftermath of two poor people for whom it did not work out. One seemed to have fallen between the freight cars - very likely due to hypothermia. European freight cars are usually locked so people can only find a “plattforn” to sit on the outside of certain tanker cars or rarely on older container cars or truck carrying cars - but the later are closely guarded. And 80km/h wind shear for hours does a lot to a body. The other one was electrocuted. Both were refugees trying to make it further north. A colleague had a case of someone who very likely was blown off a freight car by a high speed train passing by the opposite direction.

This will not only cause delays but also ruin or change a few peoples lives.

In other words: it’s a very very very bad idea.

And btw: The page you linked is full of incorrect information…