When you pay with Suica, the merchant pays a transaction fee of between 2 to 3.2%, similar to a credit card.

That's surprising. IC cards are so universally and cheerfully accepted that I assumed they had no per-transaction costs. Compare the US, where merchants can be surly about card payments.

There's a mindset difference. People are more willing to pay to reduce inconvenience for customers there, whereas here the inconvenience to the merchant sometimes matters more.