Before COVID, they almost refused me entry with that excuse at Don Muang Airport.
The truth is that they CAN ask for it if they just want to boot you. You should always have $700 cash whenever you enter. Even at airports.
But if they want to boot you that badly, they can find any excuse. But the excuse they almost always use on the paperwork (no matter what they tell you it is) is lack of financial means.
I didn't have cash, so I pulled out my credit cards like a deck of cards.
Although they said that was unacceptable, the Law literally says cash OR equivalent. So I made it difficult for them to use that excuse. I also had proof my retirement payment would be deposited the next morning. They kept pretending they couldn't read it. Photo Translation apps are cheap. And I know they could read it. I made the effort to use a yellow highlighter to point out the amount and date.
If they could have just escorted me to the ATM beyond security, I could have pulled out as much cash as they wanted to see.
The point is, never assume they won't ask. Especially if you have been to Thailand recently, or if you insist on wearing shorts, or heaven forbid, you like to wear T-shirts and sport Dreadlocks.
Dreadlocks will do it every time!
Btw, they let me in after holding me in the office for 3 hours (having to stand the whole time). But they marked a note in my passport.
Btw, each time I was away was 30 days or more. Not just a border crossing and coming back. Yet they still claimed and noted in my passport that I was trying to live in Thailand.
At least one Thai became homeless because he depended on house-sitting in the small room I kept for my short visits.
They have Databases now. If you don't show both the old & new passports (if recent) then they are more likely to reject you. That is what you fingerprints and ete scan are for.