But without Bitcoin legal status as currency/payment method, merchant can't just accept Bitcoin which also hinder adaption.
How do explain the thousands of merchants all over the world, including the USA, who accept Bitcoin then? Are they all breaking the law?
On some country (such as US), Bitcoin has legal status as money. Here's an example,
https://www.reuters.com/article/us-jpmorgan-cyber-bitcoin-idUSKCN11P2DE/. On country without clear regulation, i would guess the merchant assume it's not forbidden or dare to take some risk.