You want to say that there is no demand no supply? Yeah, you can really spend bitcoin to buy ticket, book hotel, even football player was bought with bitcoin and if I remember correctly, one club was sold in bitcoins or something similar. But why just merchants can't integrate it? If nothing, they won't be in loss with this additional payment way. Maybe there isn't really demand but everyone here talks that they want it, in reality no one does anything to get what they want
Actually, some tried to integrate Bitcoin into their payment systems
For example, Steam, Microsoft, maybe a few other big names. Steam later closed this payment channel, and the real reason, as I'm inclined to think, was the lack of people willing to pay with crypto. Otherwise, it simply didn't make any economic sense provided crypto generated enough payments to support the payment infrastructure. And that is the exact reason why merchants might not want to accept Bitcoin and other cryptocurrencies - because the costs of integrating and supporting this infrastructure might easily exceed the profits generated through it