thats their margin of error, which is why for all speeding tickets u have to be going at least 10% over the speed limit.
mate ur fine, if ur speedo said u were going 42-45, odds on u werent even going that as speedos will always overstate ur speed, and given that a camera cant book u until ur at least going 44 kmh, plus it was only 2:20, and the speed camera gets activated a little after 2:30 because some people may enter the school zone when the lights arent flashing but reach the camera when they are flashing, and speed camera flashes dead set light up the whole street they are so bright even during the day u would know if u got caught, ur fine trust me