[devmor]

>Different card schemes support different "payment kernel" parameters and have different certification requirements.

Those certification requirements are one of the biggest hurdles because they can change quite often, and unless you are a high-volume gateway, there may be no leniency for you, making simply refusing the transactions cheaper than processing them and being fined.

The digital cryptogram requirements for visa caused some major engineering expenditures for a few payment processors I'm aware of.