The article is actually a bit confusing. There was some sort of transaction involving IKEA and Ethereum. The transaction was with another company, not some random customer, though, so they might have not gone into trouble just for people. And then yes, now I got how it happened. It was a transaction that could not have happened in a different country. It was allowed because of Iceland's fiat currency being available as e-money and because it's allowed to exchange some types of digital money for others. So basically, until you have your national crypto-currency that represents your country's fiat, you probably cannot use Ethereum to pay for products you buy in IKEA.
But just the fact that they are issuing digital fiat and using smart contracts with them can be a big thing for eth if it catches on.
Eth wasn't never meant to be just money to use but to use it as the platform like for this for example.
IKEAs foray into Ethereum is possible due to a landmark regulatory decision that allows Monerium to issue digital fiat for use within the European Economic Area.
<- This was the big news to me on this article.