Actually I wouldn't expect that at all. These companies don't (seem to) hire engineers. They hire folks with academic CS backgrounds and put them in engineering

Actually I wouldn't expect that at all. These companies don't (seem to) hire engineers. They hire folks with academic CS backgrounds and put them in engineering roles, and generally they aim for younger such developers. This is like hiring undergrad and fresh graduate mathematicians to build a space shuttle. It's not a matter of competence or intelligence. It's a matter of ego and inexperience (engineering is an easily learned skill; all that matters is selecting the right data structures and algorithms from my CS [1-4]xx classes, etc.).