> Additionally I don't think there is anything wrong with client-side analytics in general since it's basically the only way to monitor performance/usage in production. And this type of thing is hard to discern from the more benign case
I think in these situations it often helps if we would find this behaviour acceptable in the real world. For example we see advertisment in airport toilets or malls or whatever. As someone pointed out, the company advertising does have an interest in finding out if the ad is effective. So would people find it acceptable if someone was following the from the advertisement and writing down which stores they go to, what they buy? I acknowledge that there is significant effort to develop technology (e.g. using ultrasound) to do this, but the efforts to do this covertly are IMO a good indication that people would not accept it if it was done in the open.
That's what I acknowledged with the ultrasound tracking (I was not aware of the tracking at Schiphol). But it just reenforces my point, if they would do it openly people would strongly object. Privacy invasion using technology is so abstract that it doesn't really relate to reality for many people (even very smart people).
I think in these situations it often helps if we would find this behaviour acceptable in the real world. For example we see advertisment in airport toilets or malls or whatever. As someone pointed out, the company advertising does have an interest in finding out if the ad is effective. So would people find it acceptable if someone was following the from the advertisement and writing down which stores they go to, what they buy? I acknowledge that there is significant effort to develop technology (e.g. using ultrasound) to do this, but the efforts to do this covertly are IMO a good indication that people would not accept it if it was done in the open.