Because you have knowledge of your own patterns, because you can change technology much faster and test many things as opposed to banks that usually evaluate enterprise super expensive software, usually neglect open source and hence don't always have the best tools. If you think the integration as an individual you probably cant, but if it's a company building on top of something like this, then it's totally possible to be better than the issuers and processors.

No reason they can't do it too, but I'd like to be able to do it as well. I'd like to be more aggressive in assuming a transaction is fraudulent.