Am assuming you bought a new crossmember off eBay?
My Colorado SVT Contour doesn't have a spot of underbody rust, but it does have some corroded spots on the crossmember, suspect Ford didn't corrosion proof that hunk of metal all that well. The condition of your friend's car is not unusual for a road salt/Rust Belt car. The primary road de-icer here in Colorado is Magnesium-Chloride, which doesn't corrode metal much at all, but does pit one's garage concrete floor.