My employers do just that - Fraud prevention is a fundamental part of our business operations. It largely involves multiple teams of full time employees workin

My employers do just that - Fraud prevention is a fundamental part of our business operations. It largely involves multiple teams of full time employees working on different aspects of fraud prevention (some of them are even Competent Developers!) a few dedicated offices, some teams embedded in regional development offices, a bunch of bespoke software and it's ongoing development and maintenance. Thats in addition to the core dev teams being aware of and mitigating any possible vectors within the platform itself. At any kind of scale it's rarely as easy as 'hiring a few competent developers'.