Note that as each person Paul points out detrains, the momentum of the trains movement and their body mechanics spins them away from the train.
And, as they entrain, the same momentum/ mechanics picks them up, although the young lady does have to pull herself up some…average height people do not have to exert as much effort, but short folks like me and she do.
But the effort is no more that that needed to take the first step up a flight of stairs.
Note also that going from the stirrup to the crossover platform was done in the same movement again using the momentum of the train, the lady takes one step up in the stirrup and the next step up to the platform, all in a fluid movement.
With standing equipment you have to both pull with your arms and push with a leg to move your body mass and weight up onto the car.
Of particular interest is the close up of the lady placing her foot in the tank car stirrup, note the movement of the train and her natural placement put the trailing foot against the trailing edge of the stirrup. in the corner as it were.
Just like the stirrup on a saddle, once your foot is there, its very hard to remove it or for it to slip, and very secure, you let the train do most of the lifting.
It becomes second nature.
One thing that was drummed into our heads was this…if the train is moving fast enough that you have to think about it, the train is moving to fast for you to safely mount.
And you were expected to tell the engineer to slow down, or stop if necessary.
And on a personal note, tank cars are for me at least, the easiest to entrain and the most comfortable to ride, note the young lady positions herself on the crossover platform behind the hand rail, so any unexpected slack can not toss her off.