Examples of solution someone thought of but decided "They must have thought of that" about?

Edited: It could be a well known story or a personal story.
That is, something that affects the public in general. For the personal part, say you’re walking driving etc., and you see a problem (or you read etc., about), which comes up over and over again, and you thought There must be a flaw in the solution, because it’s so straight forward to solve.
Is there a story that you know of where someone was told “I wish you could have come to us with that solution.”