Making statistics about sex, age, number of children, clothing choice, walking speed without consent, sounds illegal. I think it isn't forbidden for the company, but for the individual already, because that's voyeuristic behaviour.

Watching what is bought is fine, but walking around to do that is useless work, because you have that in the accounting/sales data already.

There is stuff like PayPal and now per company apps, that works the same as on the web: you need to first sign a contract. I would rather that to be cracked done on, but I see that it is difficult, because you can't forbid individual choice. But I think the incentive is that products become cheaper when you opt-in to data collection. This is already forbidden though, you can't combine consent with other benefits, then it isn't free consent anymore. I expect a lawsuit in the next decades.