@Duncan ******
most people have their TM6 (departure card) stapled in to their passport on entry into Thailand. In Phuket they put the 90 day receipt slip in the back of the passport- the one that tells you when your next report is due. As a proof of a TM30 filing can be a multitude of things (the system doesn’t give a receipt, so many use a screenshot of the website, or phone app they used) this generally isn’t put in the passport. You are correct that different offices do things in different ways but I’m guessing that that slip of paper in the back of your passport is the TM47 90 day receipt telling you when you next need to do one.