[AussieWog93]

Then where are the jet engines?

[Cthulhu_]

Turns out knowledge alone isn't enough. I mean the knowledge of how to build a nuke, a microprocessor, or a rocket that can go to Mars is public information, yet building them remains elusive for a lot of countries.

[one33seven]

It's not actually public knowledge how to build modern, small still capable microprocessors, afaik.