That’s because they’re in an illegal status when they do it. You get a visa BEFORE entering a country, you don’t break in illegally and then try to get one. Oh, and don’t conflate “immigrants” with “illegal aliens”. They’re completely different and legal immigrants don’t get arrested.
Most border jumpers are Cheap Charlies without enough money to get a visa, anyway. Usually low life types. It’s not like they inject a fortune of money into the economy. More like just take up a seat at the beer bars of Pattaya. I say the crackdown is good.
No job available for you that an average Thai person can do. It’s the law. Sorry, you’ll need some income coming in from outside Thailand every month or a substantial savings account in order to support your self here. You can’t work in the country without a work permit.
it’s been a while, but I don’t think they’ll let you change it on the SS website if it’s a bank outside the U.S. I had to send a form to the SS office in Manila, Philippines that Kasikorn Bank filled out with my account information.