A new law was passed in Germany recently, making the issue of a receipt for all purchases compulsory, however small. This was to prevent undocumented sales which didn't include VAT, doing the gibt out of their share.
However, it has caused an uproar among the environmentalists, as it has increased the use of paper, and the receipts are not recyclable as they are mostly on thermal paper. Not to mention the number of people who throw their receipts away, either on the ground or by leaving them in the trolley. If they had refused them at the till (which, of course, you can do), the cashier could have put them in her bin.
Many supermarket chains offer a "paperless" option in their app, but I think the till still has to spew out the printed receipt. I don't know anyone who does this, though.
It is definitely worth checking the receipt. I try and remember to do it whilst still in the store. Not long ago, I had a very high amount and when I looked over the till slip, I noticed that she had charged me for 12 of one item rather than only the one! I got it rectified immediately with no trouble.