A building material that is less expensive and more available may in
practice end up building a lighter airframe. The reason is that
you're more likely to be able to use the exact right stock instead of
just over building because you couldn't find or afford the expense to
buy a special piece of the lighter guage material.

Bend versus break. Old cars were build on rigid chassis, the safety
argument was that you want something really strong. But modern cars
are generally built uni-body designated crush zones to dissipate some
of the energy instead of transfering it to the passengers.

"In theory, practice and theory are the same. But in practice, they
are often very different."