I have always had a bike but used it mostly for pootling about / park and whatnot.
We have recently started doing the school run and more shopping on bikes in the interests of Doing My Bit.
The school run is a death race. I now understand why I have spent my whole life driving around and cursing cyclists. It's because they can't see what the fuck is happening on the road. As far as I can tell it's eyes front and hope for the best 
If you do want to know whether you can swerve round a parked car or turn or whatever, you crane your neck back - instantly wobbling your course - and cycling blind for as long as you are checking behind you.
Obviously my in-built twatometer stops be attaching wing mirrors to my handlebars but actually I can't understand why bikes don't have wing mirrors.
Can anyone tell me?