Hey. It’s because most credit cards are a bare silicon die with fragile wire bonds all potted in a hard resin. You can’t really get to the chip in order to attach a custom antenna, and the stock antenna is so fragile that most people can’t recover it.
In some cases the credit card use a Coil on Module design. If you melt those cards down they can be converted into an implant. I’m waiting to get the first one back from Amal after encapsulation, but in the near future people will have access to them.
