Even if you use a VPN and surf the web over TLS/HTTPS your ISP or the coffee shop you sit in can still know where you go and what you do on the internet. It's this data that gets sold to the highest bidder for a profit off what you do online.
No matter if it is the coffee shop or your ISP it's disingenuous that we, the paying customer, can't assume the company with which we spend our money isn't selling our data for more. This particularly ticks me off about ISPs and why I go to great lengths to rid them of this goldmine.
It would be one thing if they gave us the option of free internet in exchange for my data to sell so they can pay for infrastructure, but this is not the case. We pay for the service and the mine our data to sell in for even more.
How do they expect to gain any trust with practices like this?
The way they do this, even if you use a VPN, is to set the routers' default DNS (Domain Name Service) to their servers.