Well it's not just Korea that's like that either. It's only really the US, especially out of the western countries because there are laws in place that require those places to pay at least minimum wage. It's about £9 an hour in the UK.

Tipping exists here but it's never an expectancy, even if you're working for the business as I have done, because it's just extra money you get for engaging with customers.

Outside of the US people tend to only tip if the service is good. If the service is alright, in the UK it's not uncommon to give like a £2 tip or something. You still welcome them as a tip.

Tl;Dryour tipping culture comes from your abhorrent labour laws, that from an outsider seem genuinely disgusting.

It's nice that your society came to the conclusion to tip, but a shame they didn't conclude that people should be paid enough to be able to afford food.