Honestly it’s not even about the transactions themselves - individually they’re worthless - the problem appears when you get all the metadata associated with the transactions (date & time, transaction location) coupled with the metadata the mobile carrier has (continuous location updates from your phone, sites visited, etc) that makes it dangerous.
Finally who do you think pays for this? Do you really think the mobile carriers/scammers will happily give you a rebate off your bill out of the blue? The only reason they’re doing that is because there’s someone behind the scenes who’s happy to pay more for this bag of data, and they wouldn’t be doing so if it was worthless.
The main problem is also that you don’t have a way to opt-out - even if your carrier stops providing them new info (which is a long shot by itself), there’s just no way the marketing/scamming partners behind the scenes will pass that opt-out instruction along. Why would they, considering it will make all their data worthless? Not to mention, there is no traceability as to where that data has made its way, so they will not even be able to pass the opt-out along even if they wanted to.