Some ISPs in Europe offer data plans that are capped at certain amount of GB per month.
But in this europa.eu page one can read that:
The best effort internet is about the equal treatment of data traffic being transmitted over the internet, i.e. that the ‘best efforts’ are made to carry data, no matter what it contains, which application transmits the data (“application-agnosticism”), where it comes from or where it goes. The benefits of the best effort internet notably include the separation between application and network layers of the internet.
Is it actually legal under EU law to offer Internet services that do not treat all services/apps/websites equally when it comes to data caps?