Questions re: B1 rejection

Hi all,
1. Is US embassy/consulate has to provide a reason whenever they rejecting visa application?
2. Is unpaid speeding ticket one of the reason visa application can be rejected?

Hi all,
I just realized that question no. 2 is not clear, so, let me try clarify question no.2:

2. If someone used to live in the US in the past and has unpaid speeding ticket, would that unpaid speeding ticket a reason to reject visa application?