@Rob***
I do not believe Chiang Mai has ever needed a TM30 for a tourist extension. They definitely do need it for longer-term visas but not for tourist extensions. I have talked to people who extended recently in Chiang Mai and confirmed they did not need TM30 receipts. One thought they did but I enquired further and they were confusing it with the TM6 departure card, which CM immigration does want.
People mix up the different visa types, the requirements and other issues (like the queuing) are not the same in Chiang Mai between tourist and other visas.