For example, AT&T for a while has made its own streaming TV services exempt from its usage caps, while competing streaming services (Netflix, Amazon, whatever) count against a user's monthly data allotment.
This gives AT&T a distinct advantage in that users are incentivized to avoid competing services lest they face completely arbitrary and unnecessary usage limits and fees.
The company has long experimented with something called "sponsored data," which lets companies pay AT&T extra if they want to be exempt from AT&T's (again, completely arbitrary and unnecessary) broadband usage caps.
This service also won't count against AT&T's usage caps and overage fees, AT&T confirmed to The Verge: "According to an AT&T executive familiar with the matter, HBO Max is using AT&T’s “sponsored data” system, which technically allows any company to pay to excuse its services from data caps.
This has been a hard thing for some folks to understand (for whatever reason) so I'll reiterate: this is a regional telecom monopoly, imposing completely unnecessary limits on uncompetitive markets, which don't apply to the incumbent's own services.