Those who collect PII, anonymized or not, are collecting information for one or more legitimate purposes, and that same information lends itself to ends which can reasonably be construed as spying when it is inevitably exposed to those who desire to spy. Those app developers can’t plausibly deny knowing that this information sharing will occur or is exceedingly likely to occur, and by making such data collection opt-out, app developers knowingly are acting on behalf of spies, despite having no intention to directly spy themselves. If you are an app developer with opt-out telemetry or an end user of an app so developed, who is the spy or doing the spying is a distinction without a difference to my view.