From working at a CLEC (competing local exchange carrier) in the 90's:
This mindset goes back to the AT&T antitrust breakup. It was decided that phone companies would not be allowed to reject each other's traffic, because the larger ILEC's (incumbent local exchange carrier) would find reasons and excuses to cut off the CLEC's. This would be more or less a death penalty to those businesses, and the ILEC's had exactly zero reason to want the CLEC's to exist at all, so there was a lot of fear and rulemaking to prevent this.
Fast forward 30 years and the details have changed, but the mindset is largely the same. The fear is still quite real, and that's why phone spam isn't treated like email spam. If i.e. verizon cuts off incoming calls from a random CLEC in a midwestern state, that business is just over, done, that's that. It would be impossible to restore the business after your customers left, which they would do more or less instantly; there's no court remedy that would fix it. Great pains are taken to ensure that such an action is legitimate.
The rules are oriented around the idea that the ILEC's were evil antitrust actors, and the plucky CLEC's are the competition we need to protect from big ILEC's heavy hand. In a world of spam, that mindset is backward. And that mindset is changing, but because of the reasonable concerns, it's taking longer than we expect.
This mindset goes back to the AT&T antitrust breakup. It was decided that phone companies would not be allowed to reject each other's traffic, because the larger ILEC's (incumbent local exchange carrier) would find reasons and excuses to cut off the CLEC's. This would be more or less a death penalty to those businesses, and the ILEC's had exactly zero reason to want the CLEC's to exist at all, so there was a lot of fear and rulemaking to prevent this.
Fast forward 30 years and the details have changed, but the mindset is largely the same. The fear is still quite real, and that's why phone spam isn't treated like email spam. If i.e. verizon cuts off incoming calls from a random CLEC in a midwestern state, that business is just over, done, that's that. It would be impossible to restore the business after your customers left, which they would do more or less instantly; there's no court remedy that would fix it. Great pains are taken to ensure that such an action is legitimate.
The rules are oriented around the idea that the ILEC's were evil antitrust actors, and the plucky CLEC's are the competition we need to protect from big ILEC's heavy hand. In a world of spam, that mindset is backward. And that mindset is changing, but because of the reasonable concerns, it's taking longer than we expect.