Only reason I can think of is maybe they are wanting to put stakes in the pockets so when sliding a container on/off it won’t slide off the side of the trailer. Before you order a Landoll with stake pockets, you better make sure a container will fit between them.
From what I seen a lot of containers are 90” wide. The outfit near me that sells storage trailers and containers has those single* axle lightweight landolls*, they have a rub rail on the side beams to throw 2” ratchet straps on for empty containers. Seems to work for them.
We currently have a Landoll. They did put the stake pockets in via our fab shop. No rub rail on ours. We loaded a 40' container on it yesterday but unfortunately, the trailer was parked in a super icy area. Now both are back there stuck on ice. LOL. They are working on getting it unstuck now.