Mike the TM30 is the notification to immigration of where you are staying. This is filed automatically in the background by all hotels and guesthouses and SOME (but not all) condos. It's why they ask for your passport on checkin, that is for the TM30. In most cases these days it is done online, the hotel just types your passport details into the system when you register and that is it, done. So most tourists visiting here it happens completely automatically and transparently and there is no issue.
Where it becomes a potential issue is when you go for an extension- if you DON'T have an up-to-date TM30 on file, this can cause problems with your extension. So it is something you need to be AWARE of if you are staying in accommodation other than a licensed hotel or guesthouse. You just need to be sure the TM30 is filed for the time immediately before your extension. In fact it may be enough that one was just filed SOMEWHERE between the time you entered Thailand and your extension, they may just presume you are still there as long as you stayed SOMEWHERE that filed it.
The legal obligation is on the landlord and the fine for non-filing is on the landlord. Not you. But if you are standing there and need the extension, and can't get it without a TM30 filed, immigration may try to get you to pay the fine instead. The fine is small, something like 1,600B, it's not going to bankrupt you even if you did have to pay it.
So- most people don't need to think about this because their hotel/guesthouse does it automatically in the background. I have extended maybe 20 times and I have NEVER had an issue. I've never had it brought up or mentioned or asked for, as it has always been done in the background, by wherever I was staying.
But if not staying in place that registers you, and you never stay in such a place between arriving in Thailand and going to immigration for an extension, you just want to be aware of this as a potential issue.
Some more details on it below.
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Note this is an entirely separate issue to whether an AirBnb is running an illegal guesthouse, which they are if they rent rooms for less than 30 days. But again, that's their problem, not yours.