It possibly can be office specific. My Immigration Office in Maha Sarakham wanted a copy of where I am getting my pension. I gave them a copy of my Social Security statement with my Social Security number blacked out.
There are clear rules unlimited entries but Immigration Officers have the power to ignore them. Just like I believe every Immigration Office should have the same procedures and not deviate by adding extra requirements.
I agree with you. There are people who make major decisions without considering what it involves. But they are adults so hopefully the make the right choice.