Politicians are a team.  They are the 'front-man' as well as the leader of the team.  As such they don't have the time to learn everything about everything.  That's why they have a staff.  And why the Chief of Staff is a critically important position.  It's the CoS's job to gather a group of people around "His/Her Guy/Gal" having the technical and detailed knowledge and expertise one individual cannot have and has no hope of having.  

She believed in nothing; only her skepticism kept her from being an atheist. -- Jean-Paul Sartre