Driver's license isn't required for commercial cycling (but I would agree that it should be), but there are quite a few laws pertaining to messengers and delivery people that aren't being inforced -
§ 10-157 - Bicycles used for commercial purposes
• Business must be identified on the bike by name and identification number.
• Operator must wear upper body apparel with business' name and operator's number on
the back.
• Business must provide operator with a helmet according to A.N.S.I. or Snell standards.
• Operator shall wear a helmet provided by business.
• Operator must carry and produce on demand a numbered ID card with operator's photo,
name, home address and business' name, address and phone number.
• Business must maintain log book that includes the name, identification number and
place of residence of each bicycle operator; and the date of employment and discharge.
The log book must also include information on daily trips, identifying the bicycle
operator’s identification number and name; and name and place of origin and
destination.
• Owner of business must file an annual report with the Police Department identifying the
number of bicycles it owns and the identification number and identity of any employees