Not only native Germans, other native English speakers, like people in the UK use the DD/MM/YY format. Unlike people from Germany, people from the UK have no language barrier, and are a potential customer.
Yes, you are totally right. But don't overrate the language barrier: I sell a software product that is English only (localization is too expensive), and the majority of my customers are from non-English-speaking markets.
If you write the date as "August 8, 2011" it should be trivial to parse for everyone. (Except for people using different calendars)