I got an OA visa before coming to Thailand. Yes, the evisa website requires you to upload a background check. I just went to the state police website (Michigan in my case) and was able to download my criminal history in a matter of minutes for $10. Wasn’t hard at all. Not sure if every state has that option.
I tried the same thing in 2017. It’s almost impossible for an average Thai woman to get a tourist visa to the U.S. without a high profile job or something else that would compel her to return after the visa expired. And impossible to get one if they list a boyfriend in the states they want to visit. Immigration goes into it assuming they won’t come back and it’s up to the girl to convince them they will, and they rarely can. It’s because there have been too many that didn’t come back. Also, many get married there on the tourist visa and that totally subverts the K1 visa process, which is basically immigration fraud. The only sure way is a K1 fiancé visa or a marriage visa. I brought my wife to the states in 2017 on a K1 visa after unsuccessful tourist visa attempts, and we’ve been married almost 8 years now. Best decision I ever made.