As it is well know, some Immigration Offices are more lenient than the other. In your case it seems you always travel into Thailand and stay at the same address, house in your wife's name.
Immigration has that address on file and informs you that you do not need to visit them each and every travel to do this report again.
Be thankful OR if you really wish to follow the letter of the law, go to the website, make an account and make a report within 24 hours after coming home.
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