An automated system how will they check my visa?

Hi guys, this is a question for the very few "ultra" specialists among you....

I live in Thailand with a non OA multi entry based on being over 50...I went to Singapore for a few days and came back today by plane at Don Mueng. Getting through immigration went extremely smooth as the officer didn't even look at me or ask me any question whatsoever... He stamped my passport and the TM6 in the proper manner allowing me 1 year of stay as expected...

But before giving me back the passport and TM6 he decided, using his own private (I suppose) telephone to make pictures of my passport, photo page and visa plus a picture of visa and full TM6 together .... I guess he didn't need to have my picture for himself so the question is :

Since they have all computerised records of the documents why would the officer need to take such pictures 🤔🤔🤔

Not sure when this began, sometime within the last 30 days, but now when you enter Building B at The Government Complex there is an officer who scans your passport with a computer before you go through the metal detector, instead of signing in the book. Thai citizens show their National I.D. Card.