We have an evening arrival into ICN, our plan was to take a taxi, do Korean taxis take card? I really dont want to have to get any cash. If taxis need cash then I will pre-book a transfer online.
There are really only 2 major taxi networks: Kakao (as in Kakao maps), and Uber. Kakao would require you to install the Kakao taxi app. You can see if it takes foreign cards.
There is also another one called
International Taxi network, they specifically are able to speak English and Japanese, so you may want to try that.
However, I wouldn't take taxi before 8PM. Airport Railroad takes 90 minutes into city. If you take road transport during peak, expect your 90 minutes to turn into 2.5 hours.
I took a tour to DMZ, in a Kia Carnival (not the one which most tourists do), and the trip back into Seoul turned from 90 minutes to 2 hours, to around 2.5 hours to the edge of Seoul (not even inside, it took another 30 mins by metro to get back into Eujiro)
I have also seen a bunch of YouTubers who believed their hire car driver that it would take 90 mins to go to the airport earlier this year. They left their hotel in the city at 5:30 PM, peak hour traffic. Lucky the airline staff escorted them all the way to the gate, they nearly missed their flight.
I would only take road transport after 8 PM, as their peak hour start to subside from 7PM.
absolutely crazy in this day and age from a country that I thought I would have no problem arriving into without cash (and where I had no need for cash other than to buy/top-up the T-money card).
South Korea is a closed loop country (a bit like China, and maybe Japan). It shows how just because a country is a first world country doesn't mean that it's an open international country (London or Singapore or Hong Kong or Australia)