All systems with value at stake attract fraud, including paywalls (credit card fraud, obviously; circumvention too). This does not mean we give up and go home. On the contrary, Google and FB take all your data and do strong antifraud work on their native ad-inventory properties. Brave aims to do the same on your device without all that tracking, along with other projects such as https://hcaptcha.com and its protocol foundation, https://www.hmt.ai/.