Since the cars that are the priority danger (the ones most likely to get to you and hit you first) a rider tends to instinctively look to the left in the USA, and to the right in right hand drive countries such as England and New Zealand.
Peter knew that the only hazard from the front would be Mrs Tomlinson's daughter Joanne from the house opposite. Joanne has a habit of adjusting her makeup in the rear vision mirror as she motors out of the drive. But he could see, as he rode down the kerb crossing, that that driveway was, thankfully, empty.
As Peter started accelerating to normal cruising speed down the road he notice black rubbish bags sitting outside most front gates. His brain subconsciously notes this because:
(a) it is a sign of a potential danger.
(b) he didn't think it looked very classy in such a high class neighbourhood
(c) he knew black rubbish bags make good emergency wet weather gear.