Semi truck strap binder versus human jaw

Some trailers have them welded on. Many do not. The one in the photo looks like the slide-rail type which wouldn't usually be welded.
The picture you posted was of a aluminium trailer. The trailers ive replaced ratchet's on were all heavier duty, the ratchets were thicker steel
In fact not long ago I cut one off that was bent up and the owner was not using it and wanted it off. It was made out of 3/8 steel
Many dont even use straps or ratchets, they use chain and binders that catch a flat bar on the trailer sides