It isn’t a cashless society – yet – but South Korea took a quick and decisive step in that direction April 19 when on almost no notice the Bank of Korea announced consumers can now accept their change from cash purchases onto debit cards at specific stores. More here: http://www.numismaster.com/ta/numis/Article.jsp?ad=article&ArticleId=28596
Another fact that sometimes gets mentioned is the surprisingly low "collection rate" of the lower-denomination coins, such as the 10 Won coin. That one is 3.7% (in 2014), which means that when 100 of the coins are issued into the market, less than four are recovered by the Bank of Korea.
The problem isn't "coins". The problem is that countries are making coins that have no value and are merely are nuisance. If we had $5 and $1 coins with nothing smaller than about 10c they wouldn't be a nuisance.
I edited the initial post (copyright). Also see this earlier topic: https://www.cointalk.com/threads/coins-growing-in-popularity-with-public.295675/#post-2727307
