I reckon the word 'mate' is used colloquially in Australia as a mark of respect to a peer who you consider to be equal to you.
You don't call people in authority mate. But you call people you are willing to accept in the same 'social bracket' as yourself mate.
So, being called 'mate' is only condescending if you use it inappropriately to a superior. Otherwise, it is a mark of respect.
I don't know that is necessarily true in all cultures, where someone who calls you 'mate' may be being somewhat condescending.
John.