I think you can see how big the actual problem is when looking at how solved the problem is. Since the problem isn't solved and life goes on, it's probably not a huge deal. (Bed bugs are probably similar. They really freak people out, but they don't spread disease and many people don't even know that they're being bitten, so they're everywhere. People being freaked out doesn't justify a more expensive response. That said, mosquitos do spread disease and aren't exactly eradicated, so maybe my heuristic is wrong.)