Exactly. If the financial incentive is there, they'll add sufficient jitter to trick the detector, and eventually train an ML model to make it even more realistic.
The ultimate challenge is to replicate end-to-end natural human cognition, which is currently an unsolved and hard problem (and also not necessarily the main focus of AI researchers).
Are you sure? And how do you know?
There are a lot of CAPTCHA cracking services. Given the price, they are hardly sustainable even under developing country wage level. I believe they actually solve the easy ones automatically and humans are only involved for the harder ones.