I like your sense of humor. The engineers used to jokingly call this the "Orphanator -- the seat so safe only the kids survive the crash." Our marketing people told us to leave the ideas to them....
In a collision, rigidity is actually the enemy. A well designed seat should never be reusable after a crash because all the materials yielded to dump energy.
It is better to have energy diverted into stretching, bending, and breaking materials than have it channeled into a baby's body.
We don't use steel (except for one rod), but we do use a lot of 5000 series machined aluminum which is powder-coated. Aluminum is preferable because it is better for creating crumple zones where the materials yield. The other primary material we use is polycarbonate because it has fantastic impact resistance (polycarbonate is used in "bullet-proof glass"). I'll let the marketing team know their materials description failed to impress you :)
Why not make one that's solid steel and can tank a direct hit from a bus? You could make some really funny advertisements with crash test dummies.