@ Edward Miles

"And I imagine it takes a fair while longer to open a mac and replace the battery than it does to just check the serial number on a returned battery and authorise a replacement."

And wait days for said replacement to arrive with a gaping hole in your machine. Probably longer than going to the Apple store and having the battery replaced on the day.

Also, if there were a recall of batteries, they KNOW what batch goes into what number series, making recall simpler, rather than the job lot batteries that go into your Dull, Sony, Sumsang or whatever brand of Wintel laptop you own.