I suppose an auto pilot is convenient, but you're a first class fool and a danger to others if you don't remain at the helm and alert when running on auto pilot. Just the slightest bit of creative thought should warn you that the auto pilot won't avoid hazzards like floating logs and debris and other boats.
As far as operating in close proximity to other boats (something that's unavoidable in certain situations and areas), you need to know the rules, but assume that the other operator may not know the rules. You need a plan and an alternate plan. And an emergency plan.
A boat collision on the water is not like an auto collision on land. You can't get out and walk away from it.