Like the legal action that is currently protecting us from robocalls?
I don’t know if iMessage registration requires bidirectional SMS verification, though. If it does, that would be significantly harder to spoof than just caller IDs.
They do receive spam and fraud, but the numbers are orders of magnitude less than every one’s else BECAUSE it’s tied to hardware. I don’t know the details of how’s these guys got around it, but this is bad for the rest of us when phishing skyrockets.
How can you get more SMS spam on one platform than another? With SMS they're just blindly sending to your phone number, your SIM could be in any device. They don't know what platform you're receiving it on.
There were also differences in the platforms with how/when your phone number can leak to spammers and data aggregators, although I'm no longer deep enough into mobile OS or related CVEs to know current details.
Note that iPhones already receive SMS spam and fraud just like every other phone.
However, you are correct that the blue bubble is no longer a guarantee that the bad actor is using an iPhone.