Why do brake lights come on with ignition and not work pedal?

Brake light turn on when the ignition is on for safety reasons. When you turn on your ignition, the brake lights comes on to alert other drivers that your vehicle is turned on and will be moving soon. This helps to prevent accidents by giving other drivers time to react.

As for why the brake lights don't work by pressing the pedal, this is because the brake lights are activated by a switch that is connected to the brake pedal. When you press down on the brake pedal, the switch is activated and the brake lights come on. If the brake lights are not working when you press the brake pedal, it is likely because the switch is faulty or the wiring is damaged.