i think waze need to alarm everytime we're close to a speedcamera. because now it sounds only when your speed is higher than the limit, but if i don't hear any camera speed alert i can think that there aren't none of them, and unfortunately i can increase my speed when then i'm too close to the camera and it would be so late to slow down.
in my opinion waze would do better to, EVERYTIME, alert you with the voice that you're getting close to a speed camera, such as "pay attention, you're getting close a speed camera" (i'm italian, so i don't know how it sounds in english, but that's not the point of my tip).
then if your speed is higher than limit it can tell you with voice "pay attention, you're getting close to a speed camera" as well, but you can add a continuos beep until you decrease your speed.
so it would be, in the case your speed is too high, "beep, beeep, beep, beep, pay attention, you're getting close to a speed camera, beep, beep, beep, beep, pay attention, you're getting close to a speed camera, beep beep"... when you slow down it would stop beeping.
so the voice alerts you everytime, and if you wanted to accelerate you won't do that.
and if you hear a continuos beep you can get your speed is too high until you won't hear anymore the beep.
hope you got what i mean.