Even when doing it by hand it might not be easy.

Also from personal experience I think whatever they are doing also has a lot of false positive. I managed to not have a twitter account for so many years, but created one as I wanted to post a response. I think it might worked once, now whenever I post something it just refuses (forgot exact message but essentially something that my post looks suspicious). I don't think I will be going back.

That makes me believe they might be also losing many real users.