Similar problems, not the same problem. There's nothing you can do to get aluminum's yield strength above zero; steel and iron can bend without damage, aluminum can't. Steel, meanwhile, can end up anywhere between "lead" and "glass" as far as hardness depending on how you temper and alloy it. Bronze and copper are actually easier to work with because they don't require an inert atmosphere.
They're using MiG welding robots. That means they can do anything that can be wire-fed. You can wire-feed stainless, but it's much better TiG welded than MiG welded. Also worth noting: most every bridge, aircraft, car frame, etc you've ever seen is riveted, not welded because when you care about the strength, welding really fucks with your mojo. You can weld something and then re-temper it if it's steel, but everything else is tricky.
I used to be a "weld everything" kinda guy until I discovered that you can really break things a lot by heating them up to molten. heating them up to molten in a reducing atmosphere? Yeah, asking for trouble.