Me personally, I prefer using cash because I use the spare change to charge up my transit card. Here in South Korea, most mom-and-pop shops simply decline all card transactions to avoid taxes and fees. A few weeks ago I ate a 5,000 won meal (around $5). I only had 2,000 ($2) in my pocket so the owner told me I can just pay 2,000 for the meal!!! It's that serious.