why aren't the frame rails of TT set evenly from the sides?

"why aren't the frame rails of TT set evenly from the sides?"

Having used Amish Craftsmen on a few things in the past reading tape measures and plumb/level/square are not high on their priority list.

Then watch how fast they attach the floor HERE

And that was before they were "acquired" by Thor which I can guarantee did not increase any level of quality be it in materials or actual assembly.