The nations have some of the best economies in the world. Bitcoin is gradually becoming a currency of the rich, so you don't expect companies in developed nations to adopt Bitcoin payment because most people are below the poverty line. These nations also have high literacy rates which helps in Bitcoin education and adoption. The bottom line is that more people use Bitcoin in these nations, which will encourage companies to accept Bitcoin payments. American and European nations also have advanced infrastructures and technology that make Bitcoin transactions easier and more convenient. Some countries in Africa lack electricity and internet facilities, therefore you don't expect companies to promote Bitcoin payments. Another reason might also be government policies. Most of these nations that are experiencing an increase in the number of merchants because these nations have favourable policies.         


Privacy is one of the benefits of using Bitcoin for making payments. The high transaction fees might be discouraging but privacy is also a great advantage. Using decentralised wallets and platforms is the best if you want to maintain privacy. But those who don't care about privacy use centralised platforms.