It requires continuous expansive improvements. It is like real world. Building a system robust to frauds works on the short term, but on the mid and long term is impossibile. That is why laws change, evolve, we have governments and so on. Because system reacts to your rules and algorithms, making them less effective.
And these continous expensive improvements are done daily, but it is a difficult job
Problem is that many sites don't work because of anti-ddos and anti bot measures.
It is a pity
It is not at the moment. Models are built on the assumption of stability, i.e. that what they are modelling doesn't change over time, doesn't evolve. This is clearly untrue, and cheating is a way the environment evolves. Only way to consider that, is to create a on-line continous learning algorithm. Currently this exists and is called reinforcement learning. Main issue is that methods to account for an evolving environment are still under active research. In the sense that methods to address this issue are not yet available.
It is an extremely difficult task tbf
From your link