(We don't have 'crosswalks'. 'Fire hydrants' don't look like that. 'Parking meters' don't look like that (or any one standardised thing really). Traffic lights don't look like that and how much of them am I meant to click anyway. School buses don't look like that. Trucks don't look like that. I'm sure there are more.)
Lot's of things where you might think you know what you're doing, but are actually doing it wrong because you lack cultural context..
I'd heard it in films before captcha, but had to guess it's the zebra crossing looking (the meaning is different though, I understand) things. Now it's just something I'm familiar with because of captcha, even more so 'parking meters'. Which is just weird, why do I have to learn something mundane about a specific country in order to prove I'm human and allowed to use a global website?