Deconstructing the urban myth.
There is a common perception that they all ride track bikes with no brakes.See parody below.
A handful do, yes.
In NYC though, food delivery would outnumber bike couriers 10 to 1.
I did both, often in the same day when I worked in NYC. Courier by day, food delivery (for Mama's in the East Village) by night.
Food delivery only pays in 'tips' so it can be a real heartbreaker to ride 10 block, walk up 5 flights of stairs to only make a dollar.
You do see some 'interesting' things when you deliver food though.
Here's a mix tape of a morning in NYC. If you've never been, it's as diverse in bikes as it is in people.
Have a great weekend, ride safe and take this lady's lead - wear a helmet.