Alex and all,

It is standard safety practice to use the side ladder when climbing a car so that is why scuff marks do not appear on the end ladders.
Here is a safety film on proper practice that may be useful on this point, starting at approximately 12:30 minutes into film
is section on proper practice to use ladders

https://www.youtube.com/watch?v=WNqPV9EOskQ

It is also a great film to watch for all the great freight cars and details shown.

Hope this is useful,
Dan Smith