rear tyre wear

I queried on my last A3 with Bolton Audi as the uneven wear seemed excessive to me and to my local tyre fitter, who had also seen similar on his mates A3.
They guy at Bolton thought it strange, took some photos and said that he would send them off to Audi (in Germany, I think) and get back to me. I have not heard anything back from them since and that was over two years ago.
I've now got a sportback and have been keeping an eye on things. The wear is a little uneven, similar to yours, but nowhere near as bad as the previous car so not worried.
Probably another "quirky characteristic" of the car!!!