Putting aside the fact that at least 50% of the world doesn't speak English and might not even know what "cheese" is, a lot of the world does not subsist on dairy products or use cheese and will not recognise images of cheese. Neither will they understand the traditional American schoolbus which is a very distinctive thing and will pick any old bus that appears on the photos as long as it looks like a large motor vehicle. Very few people percentage-wise will know what "crosswalk" or "sidewalk" or "mailbox" mean because these are very specifically American terms

Just for context, 65% of India is rural and a ton of these people do not have access to the internet and will have zero idea how to get through these arcane captchas. The internet is effectively locked off to them