Before picking traffic lights it was writing numbers and words. They came from street view and googles project to scan books. You can now enjoy the fruits of that in google lens for example.

That game that played like Pokémon go before it was used to have people walking into alleyways and such for google maps.

Captchas are needed because people are bastards. You can't even start to imagine the insane amount of time and resources dedicated to fighting bastards.