Germany is a cash country and the 1 EUR thing is quite popular. However, it is more common these days that people use specially crafted tools on their keyring to unlock the carts [0]. Before that it was plastic coins because the locks had drawers. The plastic chips are actually popular just because you cannot pay with them and this will not fail to have one the next time shopping. If hacking is more convenient than the real system, it will become mainstream.

[0] https://www.amazon.de/Caianwin-Shopping-Trolley-Stainless-Re...