Henri Wilson wrote:

just show me evidence that light from differently moving
sources really does travel at the same speed through space.

Take an introductory physics or optics course at any college
or university. Sydney, Canberra, and Melbourne should each
have several capable of serving your needs. Talk with the
instructor before registration if you can and tell him or her
that you wish in particular to learn about measurement of the
speed of light from moving sources. The measurement is not
difficult but it is something that takes a bit of effort and
initiative. Getting the help of other students makes all the
difference in the world.

Leonard