I don't seem to understand why the only type of tense used in duolingo is the simple tense.
Agreed. Present Perfect makes more sense here, as presumably they will continue to change the world.
Agree also. "Science and technology has changed the world" is more natural
Sometimes the definite articles have to be translated even if it creates bad english Sometimes they cannot be translated . Make up your mind if I may be so bold!
I took a chance and wrote "Science and technology have changed the world." It was accepted.