My data points come from monthly travel to Asia over the last 15+ years using Visa, Mastercard and in the last 1 year, Amex.

1) Previous poster said Citibank's ATM rates were good compared with Chase Visa cc. The difference is because both are using different networks, Mastercard vs Visa. Rates are set differently. Not because Citibank has a better rate than Chase.

2) Your first link to forex rates are for cash or bank transactions, not ATM

3) The 2nd link (Visa) shows Visa actually beating the best cash rates 31.40 vs 31.33 (SIA) on Jan 30. However, because Visa calculates their rates daily, sometimes a spot cash rate, particularly if the rate fluctuates widely, might be marginally better. In some countries e.g. Vietnam, the spot cash rate appears always better for pristine 100USD notes.

For ATM, it is the interchange network (Cirrus MC, Plus Visa, UnionPay etc) rate + the (source of funds) bank % cut (if any, e.g. Schwab is zero) + the transacting bank's ATM access fee if any (Thailand: 150B or 220B). In the last one year, I've done around 20+ transactions in 7 Asian countries - all have followed this formula exactly.