Why does the Northern Territory still let people set off their own fireworks on Territory Day?

People in the Northern Territory can legally light their own fireworks from 6pm to 11pm today.  (ABC News: Che Chorley)

For five hours today, people in the Northern Territory will be able to blow up fireworks with no permits or training, to celebrate Territory Day.

It's the only time in Australia that the public sale, use and possession of fireworks without a permit is legal.