At a coffee shop, you can’t use a single-use disposable plastic cup if you dine in.
You can only use a disposable cup if you take your order to-go.
Even if you are to leave the café within minutes of sitting down you must use a reusable cup as this rule is enforced by the government.
I admit, it’s inconvenient from time to time.
Sometimes I wish employees were more flexible with this rule, but policy is policy, and the store could get in trouble if they made exceptions.
Busan Travel & Living 