Agreed, I don't think they check much after the interview. When I had my interview, i have listed all my tickets (< 10) on the N-400. Wrote down that no fine was more the $500 and I brought a letter in from the local court saying I didn't have any problems w/ the law.
Anyway after the officer said he would recommend me for naturalization he told me that if they he needed more documentation they would contact me. That didn't happen instead I got my oath ceremony invitation letter.
I think that if you didn't raise any red flags at the interview there will not be additional background checks.