Why is light the same frame of reference for all, but not other energy, such as sound?

Question

For instance, if a person were to shine a flashlight away from him, his friend would go towards the light, and the person shining the light would stand still while pointing the light in the same direction, the light would be moving away from you, and towards your friend.

I KNOW I HAVE MAYBE SAID SOME THINGS THAT ARE INCORRECT, BUT I AM JUST TRYING TO UNDERSTAND THE CONCEPT.

Answer 1

Light is not a frame of reference. It's just that no mater what reference frame you are in, you will measure a constant speed for light. Sound is affected by motion because sound moves through a physical medium like air or metal. EM waves (light) don't need a medium to propagate.