That's for two reasons the first is they don't have a uniform because they are not a unified organisation. We have Scouts, Sea Scouts and Air Scouts in the UK which all have slightly different uniforms but we have the same rules to abide by.
German Scouting would be like also including Girlguiding, Cadets and Boys Brigade. We all have basically the same underlying goals of teaching kids useful skills and teamwork but slightly different ways of going about it.
German Scouts like practicality and functionality in their uniforms not sure blue gingham shorts would fit with that description.
Oh and completely aside from whether kids should wear them because of the way they look or potential bullying, I am a Mum whose daughter wore these dresses she flat out refused those shorts because they are so poorly designed. She happily stole her brothers grey shorts because I bought the cargo style and she coveted the pockets.