hCaptcha is in fact tested this way, and has pretty consistent accuracy across hundreds of countries: https://www.hcaptcha.com/post/do-captchas-really-discrimi

hCaptcha is in fact tested this way, and has pretty consistent accuracy across hundreds of countries: https://www.hcaptcha.com/post/do-captchas-really-discriminate-against-non-americans https://www.hcaptcha.com/post/do-captchas-really-discriminat... (disclosure: work there)