It might be possible that people order half a kilo, I just never hear that. People here usually use pounds, i.e. ein Pfund, zwei Pfund, ein halbes Pfund, and of course they are not talking about metric pounds. I never ordered anything in the 50 kilogram category or witnessed somebody doing it, so I am unsure if people use zentner, but I suppose so.
North Germany here.
Also: What young people do and don't do, I really do not care about. I am in every aspect closer to the old guy sitting on a park bench shaking his head about them, than to them.