I was at the bank yesterday getting something notarized. I explained to my daughter Lily that a notary verifies that somebody with the person's ID has signed their name to a document. She asked a very sensible question: "Why don't they take a video of you signing it?"
Why not indeed? The cost would be trivial. In fact, holding up the document and the ID to a cheap camera would reduce the cost, already trivial, of the notary recording that the signature had taken place.
Now that Lily has thought of this idea, how could she profit from it? Or, since it isn't patentable and she isn't of an age to go round doing consulting work for state governments, how could she get the idea to someone who could get it implemented? (in which case, she can get some credit for it too and use that on her college applications seven years from now…)