We provide a spam reporting app in the iOS app store.
We have discovered spammers are sending MMS with images, videos, and audio files. Spammers are also hiding URLs in the subject line. When users report spam using the iOS spam reporting extension, none of this information gets passed through to the app selected to receive the spam report.
Also, some spammers are using phone banks with iPhones to send iMessages, which are then unreportable except to Apple.
In other words, SMS are reportable, but MMS content and iMessages are not. Just sharing this in the hopes someone at Apple see this message and might fix these loopholes that spammers are exploiting.