Can someone explain German customer service to me - so many people working are extremely rude

It is one of my least favorite parts of living here. So many people in customer service roles here from restaurants to IKEA to shops of all kinds have an attitude of you should be thankful they showed up for work instead of them thinking how they can help you.

It's almost like people take offense to you asking very relevant and basic questions - like do you have this product etc etc. I have had countless experiences of people in customer service being snappy and outright rude. Which is crazy to me - they should be wanting me to buy their product not ruining my attitude.

How did it come to be and how is it acceptable for people in customer service to treat customers so poorly? I am in Berlin so perhaps that adds to it too... But my god is it so hard to be nice, neutral at least, just please cut out all this rude disrespectful crap.