I very much doubt people are having their accounts closed. Not being able to open one, sure, that's not surprising, but unless you're a scammer or have used your account for nefarious purposes, it's very unlikely to be taken from you.
Aside from some Burmese DTV holders, pretty much everyone else has no issue with entering and exiting whatsoever. It's almost guaranteed unlike if you're on a visa exemption or tourist visa. The DTV is a good visa to have, except for the difficulties with banking (which will hopefully change once the current crackdowns come to an end).
You clearly have no idea how Thailand operates. There is no consistency. Whereas a tourist visa holder may find it next to impossible to open a bank account, a DTV holder might have a different experience.
What you're saying is nonsense. It's up to the branch and each individual you ask will say something different based on what they believe to be correct. Nothing to do with "saving face". What a nonsensical assumption on your part.
Cars not in your name can be taken to Laos as well with a letter of authorization. However, generally, rental car companies won't issue this letter (in rare cases they might). You can also self-drive a rental car in Laos, visit Avis. I know the general manager and founder of the company. Their cars are allowed to be driven into Thailand.
They will if it's a country, which doesn't stamp your passport anymore and there are an increasing number of those. Try Hong Kong, Singapore, Malaysia if using the autogates, even Cambodia (if arriving by air).