Meanwhile, your payment card provider is probably doing that many transactions per second just in the small city I live in.
[1]: 65,000 Transaction messages per second
[0] https://usa.visa.com/run-your-business/small-business-tools/...
[1] https://usa.visa.com/dam/VCOM/global/about-visa/documents/vi...
Also, consider there are other networks like MasterCard:
[2]: MasterCard’s 2012 annual report asserts that its network can handle more than 160 million transactions per hour with an average network response time of 130 milliseconds. Operating 24 hours a day every day, MasterCard reports that its processing systems have consistently maintained availability 99.9 percent of the time.
[2] https://www.philadelphiafed.org/-/media/consumer-finance-ins...
Cc processors on the other hand are on the hook for fraud, so they are checking every transaction to make sure it doesn't match certain hueristics that could indicate theft or fraud.