Comment by jasoneckert

When looked at from another angle, opt-in does work.

By adding that extra step forcing users to be aware of (and optionally decline) the vendors collection of personal data, it adds a disincentive for collecting the data in the first place.

In other words, opt-in can be thought of as a way to encourage vendors to change their behaviour. Consumers who don't see an opt-in will eventually know that the vendor isn't collecting their information compared to others and trust the product more.