CS,
I would have to agree with you, as ATC can issue you with a SID like DirectAnywhere has said that directs you to turn below 500 ft.
Also company surveyed OEI departures may require a turn at 400 ft before the aircraft accelerates to reduce the turn radius, and therefore the associated splay.
Float planes taking off in rivers can turn below 500 ft to avoid a bank, helicopters operating into city heli pads can do it, oil rigs etc etc.
Aircraft for CAR 166 means "any machine or craft that can derive support in the atmosphere from the reactions of the air.", not just aeroplanes, likewise an aerodrome does not have to have a long black runway.
Obviously this does not apply to DoD, Customs, or Police aircraft.
