It often doesn't even matter to click wrong boxes to a certain degree. Green or red points are usually accepted as traffic lights (often no need to click the whole traffic light) and anything white painted on a street is usually accepted as a crosswalk and so on. Skipping/verifying the second task without even bothering to look at it (i.e. immediately after clicking "next" on the first one) usually works well, too. The AI based on the ML at work here seems not to be very sophisticated.