Thomas Mitselis posted about TM30 reporting in Samui, it’s my experience (and others) that Samui immigration in Maenam are only asking for for proof of TM30 when you apply for a new extension. I’ve never been asked for proof whilst doing 90 day reports or had to notify them when I’ve checked into a hotel in another province, they’re not bothered - at the moment.
TLDR : Answer Summary
In Samui, immigration in Maenam typically requires proof of TM30 reporting only when applying for a new visa extension. Many expats have not been asked for TM30 evidence during 90-day reporting or when checking into hotels in other provinces.