No it is not just laws that prevents companies from selling their secrets but also
commercial interests.
No amount of money will make a jet engine manufacturer sell their tech to you.
Rubbish, engine tech is always evolving. Money got from sale of tech, goes into developing next gen tech. As a matter of act Europe was lobbying to allow for sale of defence goods to china, inspite of knowing that the chinese will copy their goods. Same was true for Israel. Its only the law that keeps them away.