Schedule 40 pipe has a lower tensile strength than hrew tube.
Hrew tube has a lower tensile strength than hrew-dom. "Dom"
The cold working of the tube through the mandrels increases the strength over normal hrew.
I'm willing to bet that bouncer chassis was hrew, not sch 40.
I'll post specifics and data later.
I have used some sch 40 on some straight, non bent pieces, and gussets, as well as some areas that were prone to rock bashing like rocker steps etc, that were not critical for protection.
The problem with pipe with a seam, is that it is exponentially weaker, when the seam is on the outside of a bend, in tension. This makes the pipe/tube much more prone to splitting and losing its geometry and it's strength.
Remember. Even dom has a welded seam as it begins as hrew.
Chromoly has a higher tensile strength that everything above, but becomes brittle near the heat affected zone after welding, without post weld heat treatment or normalizing/annealing.
Anywho, that is way too much actual tech for this thread that will for sure be lost in translation.
