I'm not sure if I missed something, but the top answer says:

The question is what happens here. The theory behind it is pretty easy and the good thing is, it explains what you have to do from any (meaningful) viewpoint. Let's use a simple cylinder graphic as example to explain what I mean

I'm pretty sure his example is at a contorted sideways angle because it demonstrates that you can line it up from any angle. The OP in the question could reasonably expect that the customer will be facing the handle from directly behind it when they push the trolley, and adjust his maths accordingly.