Why are alloys considered as homogeneous mixtures?

Alloys are mixtures because the elements that make it up are physically together, not chemically joined together as in a compound. To be plain and simple, a homogenous mixture is a bunch of molecules so close together (but not chemically joined) , that you can't tell them apart. 
Example: Cola--made up of water, sugar, and carbon etc, but I can't tell it's a homogenous mixture just by looking at it

I think now you understood the concept.