Really? I never get them (here or elsewhere) and it just gives me the tick and lets me go on without making me choose pictures. I only ever get it if I'm signed in incognito for some reason or have cleared cookies and history recently.

I suppose it may have more to do with history and cookies than being signed in then..

Yeah, and I always get it when I have to do something like surveys and such. To the point it almost becomes annoying.

What do you mean almost? Doing captchas has always been annoying...

I suppose the point is they have to be less than obvious so they foil bots but whether it's trying to decipher some blurry distorted text or decide whether 'click all the boxes which contain signs' means the post of the sign as well it's always annoying... which is why I'm glad I don't seem to get them.

I've assumed it was being signed into Google (as presumably they can just link to my account history and see I'm a genuine person) but it's possibly just a cookie that gets set once you get it right once.

The only thing i had was adblocker which i turned off when i was trying to redeem a code on 2nd try but anyway just tested it by writing test and this is what i get currently connected to my youtube google account.