It is not that bots cannot be trained to bypass CAPTCHA click here. If the programmer sees all the CAPTCHA challenge when he or she is making the bot, cracking them is child's play.

It is like a policeman trying to find out if the ID given is fake or stolen. He will ask random information like the birthday or address.

Crooks that do not have great memory will be caught out. The rest of the public with real IDs would have memorized the info.

If all cops to ask the same question, you can beat the system. But if cops get suspicious after a certain amount of time, the bots programmers might not want to waste time making bots too smart to beat the interrogation. Even if you answer the first question correctly, the system might try a different question later.

Like the movie the Imitation game, it is not useful to beat the system as the other side will only change the game.