Except when it doesn't. Every so often it suddenly spams one with sheer number of captcha on sites that use the Google's Recaptcha API. Then you have to solve detect the houses, cars, store-fronts, deceiver plates and street signs several times successfully to move on or be prepared to solve several more captches to be allowed to move on. I would wish Google fix Recaptcha. It used to be so good.

Are you using an adblocker or any other privacy extensions (PrivacyBadger, Disconnect, etc.) ?

If you are, Google will spam you to death with captchas; it kinda makes sense because captchas are getting easier to solve for machines, so apparently the new test of humanity is whether Google can track your activity on other sites.

Whenever I get spammed with captchas I assume the site is somehow redirecting them to me from a bot.

I hate it when I fail the Turing test, and can't log in to stuff.

Obviously I am 99.99% sure I am clicking correctly, yet Recaptcha displays me another and another captcha, until it lets me move on. Is it a system bug or maybe their bot detection got quite unreliable?

Neither. When Google finds someone willing to train its AI for free, it likes to take advantage.

You are a bit sarcastic. What can a user do? Either he continues solving "train their AI for free" until the let you move on or you leave the site?

You can complain to the site operator. Google is not forcing their captcha on websites. If enough people do that, perhaps site operator(s) will take notice. Tell them exactly what you don't like so they don't eventually change to different vendor, but same annoying captcha tech.

I remember one particular set of pictures with both buses and coaches (and some with neither) on it, and it asked me to click on the buses. It said I'd got it wrong, but presented an almost identical set afterwards, and I included the coaches, but that was also wrong.

I've seen this happen, and I think it was because the IP address was previously used for craping of some sort, or somehow set off some flags at Google. VPN providers can cause this because sometimes their IPs are used for just such things.

It doesn't seem to matter which images I click, it lets me in after a while anyway.

I must be really unlucky in that I regularly get pretty challenging captchas which require a lot of tries before it lets me through. It's frustrating enough to make me avoid future visits to sites which use their captchas.

I take it you don't use a VPN. I often have to pass a captcha just to use google search when in an IPv4 address. (Considering that ISPs are now allowed to sell my data, using a VPN seems to be an obvious choice.)

It's annoying to the point that it's pushed me to use DuckDuckGo more often and I tend to avoid platforms that require me to continually take their captchas. I used Discord for a little while, but once it started asking me to verify my humanity again periodically per session, I booked it.

Have you tried Startpage? Lets you Google search via their proxy servers, no issues with tor/vpn that I recall.

This might be exactly what I need. Thank you!

So, you're traffic is coming from some provider that purposefully obfuscates info and your traffic is mixed with a bunch of other people's? I can't imagine why they view you as less likely to be verified as a real person...

I'm not saying that it's an unreasonable assessment on their part, but it is a large annoyance.

My question is: are they doing this to simply get more training data for image classification, reduce server load by minimizing automated traffic, or to sanitize their queries for human input for NLP models?

> My question is: are they doing this to simply get more training data for image classification, reduce server load by minimizing automated traffic, or to sanitize their queries for human input for NLP models?

As someone that works in an industry where CAPTCHAs have historically played a large role, and some players flat our use technology to bypass them, and do so using proxy and/or VPN services to get good IP addresses to do so, I imagine those automated systems both corrupt the CAPTCHA system somewhat, since it looks like a large corpus of humans behave in a certain manner and it's not humans at all. It likely also causes those IPs to be considered by the CAPTCHA system as highly suspect whenever encountered.

For your next questions, the industry is event ticket resale, and no, we don't do that (there are aboveboard ways to function in this market that rely less on brute force and more on data mining and analysis for specific targeted investment, and sometimes long after it's been on sale).