Web agents are increasingly central to how AI systems interact with the web — automating research, extracting structured data, completing multi-step workflows. But in production, many of them fail. Not because the agent logic is wrong. Because the browser infrastructure underneath isn't built for the modern web. This article explains why protected sites are hard for automated agents, what kinds of solutions exist, and what "infrastructure-level" actually means in practice. What Makes a Site "Protected" Most developers think of site protection in terms of CAPTCHAs — the visible challenge that asks you to identify traffic lights or type distorted text. But modern access management goes several layers deeper. When a request arrives at a protected site, the system evaluates multiple signals simultaneously: IP reputation. Where is this request coming from? Datacenter IP ranges (AWS, GCP, Azure) are associated with automated traffic by default.…