We did not solve email with legislation. CAN-SPAM is a joke, and you as an individual have no recourse when you get spammed: https://www.law.cornell.edu/wex/inbox/can-spam_and_consumer_...
Email is tolerable because gmail and others implemented software spam filters. Gmail did so because they were in competition with other email providers and it was a way to get users. The incumbent phone carriers have no incentive to compete here.
Other platforms did better solving the spam problem, so most people simply don't use SMS/MMS anymore. The kids and young adults all moved to Telegram, Discord, Whatsapp, iMessage, etc.