My old ING-DiBa credit card was transparent, you could see the wires of the NFC-antenna even with the card lying down. Not any more. Now it is opaque, and even against a strong light source, you don’t see anything. I just received a card from DKB, in a new look: black, and completely opaque.
Why? Probably to prevent people from disabling the wireless capabilities by cutting the antenna, e.g. by drilling a small hole.
I don’t mind wireless. But I do mind transactions without any safeguard. I was asking my banks to always require a pin on wireless transactions. They cannot do this (they claim), as the vendor sets the limit (typically €25) and takes the risk.
I sympathize with the industry, as wirless terminals are cheaper and easier than a card reader. But until I can enforce secured transactions, I will disable NFC, thanks, but no thanks.