I agree with you, it seems insane to be asked for these documents at the immigration counter. Verbally asked, yes, but asked for proof while holding up others in line seems crazy.
Questioning is OK but if they start asking for documents that most people won't be traveling with, that will become a problem. Now I do travel with my laptop but I'm not planning on taking it out to show to an immigration officer. Luckily, my Thai is fluent and I have a way with officialdom, which allows me to breeze through in a way that most farang won't, but equally, I don't have a questionable immigration history either. I haven't used a visa exempt entry or tourist visa since early 2015. I've never overstayed. I've never held an education or volunteer visa. I'm not Burmese, Indian or from another third world country who's nationals often get scrutinized. I got my DTV legitimately without an agent.
That's not practical for most people who are traveling. I am able to answer questions, provide my business card but I'm not going to be traveling with the original approval letters.
800 - you do know that 1) you have no obligation to check or respond to private messages (I sometimes only see them a YEAR after they're sent my way) and 2) there is a block function, which is very useful when dealing with trolls or just anyone you don't like? I've blocked well over 200 people over the years myself and perhaps 5 people in this group.
Yes but only that border does that. I wasn't bouncing either but spending several days in Myanmar. If you don't use an agent that's what happens at Saphan Pla pier. All visa types seem to be asked, but they weren't too insistent. They might have been had I not had a visa.