If you hire a loss prevention officer to protect your store, you're directing them in how they collect information about your customers and how they handle that data.

The closer equivalent would be if I purchased Square point of sale tablets to accept credit card payments in my store, and then Square sent their own loss prevention officers to my store to monitor my customers without telling me about it and kept the data for their own purposes.

What if you hire a 3rd party security contractor (also common)? i.e. rent-a-cop

In this case Stripe does tell store owners what they're doing if they would have done due diligence and examined the service more.

Either way, not sure why everyone's coming after Stripe instead of the stores that decided to use it

The HN crowd likes to freak out whenever data is being collected...