I was more surprised to see that the ACM does not have a Knighthood.
Have we stopped awarding them to Australians (or have they stopped accepting them) since they move ever further towards the edges of the Commonwealth?
Not since 1976, with the introduction of the Order of Australia. AK and AD (Knight and Dame) were abolished by Bob Hawke in 1986.
ACM Houston is a Companion of the Order of Australia (AO), the highest award in the Order.