Our payment systems that handle the firehose of data are distributed, thus we cannot have a single point of token generation, which cannot scale up for the continuously increasing volume of tokens we need to generate. If one tokenization instance becomes unavailable, we need to still keep the platform running — including tokenization — while we fix it. The only way to be fault tolerant while scaling up is to be able to keep the system consistent while being distributed, and using UUIDs is the first step towards that. UUIDs have a one-in-17 billion chance of collision, and are generated using hardware entropy.