Web client to web server: I'm not sure I can trust you with my user's privacy, so I'm going to give you as little cookies/telemetry/side channels as I can. Web

Web client to web server: I'm not sure I can trust you with my user's privacy, so I'm going to give you as little cookies/telemetry/side channels as I can. Web server to web client: I'm not sure your so-called "user" represents a real-life human user. Can you at least prove that you're a real-life web browser? Web client to web server: hmm, well okay, here's my User-Agent header. Just curious why you care about who's sending the request? Web server to web client: Still not convinced, can you give this CAPTCHA to your so-called "user"? As to you second question: bots, spam. And the ad network sponsoring me doesn't trust my tally. Web client to web server: My human hates CAPTCHAs, and AIs are better at it anyway. Web server to web client: Ghrmbl. Okay let me talk to Widevine/FairPlay/PlayReady DRM or your microphone/gyroscope/battery level/uptime/... ... The arms race of surveillance enshittification.