What I think this is: as a reward to themselves for not stopping the tidal wave of fraud and phishing distributed via sms, they're going to charge businesses to message you in verifiable manner. So when your bank, ups/fedex for package delivery, walgreens/cvs for prescriptions, etc want to contact you google is going to charge.

As a reward for helping make sms untrustworthy, they're going to tax trustworthy communications.