-Post removed as rate limiting on HN does not allow me to comment and keep the discussion going-

Edit: Please stop commenting below as I can't reply anymore

The fact that it can be deduced in some cases by some people is missing the point that a test of humanity shouldn't be country specific at all.

>The ones with liveries on the side that are all the same color.

Which is also not true for some countries...

nephihaha an hour ago | parent | prev [-]

Not really in some countries taxis are specific vehicle types and clearly branded. American ones are ordinary cars with slight modifications.

"slight modifications" it's entirely

In most places taxis can be identified as: having a specific color/color pattern and/or a ceiling fixture

It is by design because you want taxis to stand out from other vehicles

retired an hour ago | parent | prev [-]

And in that case the CAPTCHA would still work, as the vehicles are of the same type and have clear branding.

	▲	onion2k an hour ago \| parent [-]
		Is 'identify all the similar cars?' a valid capcha though? Surely knowing that something is a taxi is the important part of the test, and a good capcha would through in a branded car that isn't a taxi, which non-Americans are far more likely to fail. Remember that the goal here is to test that a request isn't coming from a computer, and 'identify all the similar things in these images' is really easy for a computer.