i apologise if the following statements may sound a little unscientific, or appear to beat about the bush. Now if two positive charges are travelling together side by side with a certain velocity wrt to me, i will witness a magnetic attraction between them. But if i am travelling together with these charges; i.e. they are stationary wrt to me, i will not witness any magnetic force. So whether you witness any magnetic force or not depends on your reference frame. Light itself is an electromagnetic wave. But according to special relativity, the speed of light is independent of your reference frame. So the existence of a magnetic force between 2 charges is dependent on your reference frame, but the speed of an electromagnetic wave is completely independent? Although both seem to be manifestations of the electric force. This gets even more confusing when you realise the only way to explain the magnetic force between both positive charges is to use special relativity and lorentz contraction. So its kinda like using the invariance of one electromagnetic property to demonstrate the variance of another electromagnetic property.