I thought exactly the same. I seem to remember a documentary/consumer affairs program showing DHL staff throwing anything marked as fragile, though it was about 10-15 years ago if I recall correctly.I know the instructions said to mark the package "fragile" and I see that some people have, but I wonder if it makes any difference to how the couriers handle them.
The cynical part of me thinks that they will throw them harder if marked fragile.