That's how it works in the US as well. You might be conflating Apple Pay with Apple Wallet, which stores your credit cards for tap-to-pay. Most people in the US use Apple Wallet/Google Wallet to digitally store their credit/debit cards, and use those cards to pay at the store by tapping the POS terminal.
For example, I use Apple Wallet for nearly every transaction, but I never use Apple Pay/Apple Card as the payment method.
The method described in that guide is basically how you setup Apple Pay.
Apple Wallet is simply where the card is located on your phone. Once you use it to pay, you will use Apple Pay.
This is one of the reasons why Garmin Pay is pretty useless here. Most banks only support it with credit cards and a lot of stores do not take credit card-based contactless payments (with some exceptions like e.g. Jumbo and Decathlon).
The reason is that debit cards have been the standard cards since the beginning. Nowadays more people have a credit card for online shopping outside the country, etc. But when I was young my dad had a credit card and that was fairly exceptional.
I'd buy myself a shitload of rupees if they were still around. Such a missed chance.