Andy Burns wrote
F Murtz wrote

all in Australia use and have used 2% or 5% (copper silver
phosphor alloy) For joining copper pipes extensively in
normal water piping for residential and commercial for years

How much tin does Australia mine?

Hell of a lot more than Britain.
http://www.indexmundi.com/minerals/?product=tin

Could it just be you have lots of copper/phosphor and
silver is what makes those work in combination as a solder?

Nope.

I have been assuming that we just copied places like the UK but it
seem we are ahead and copy world best practice instead of the old

Yet you don't know if or how it's "better"?

It must be if its specified for some work.