I asked her why they wouldn't accept Bitcoin payments but have the walls decorated with bitcoin stickers, banners and crypto wallet ads. She explained they have some sort of franchise deal and get paid for keeping the ads on the wall but they don't really know how Bitcoin works or how it can positively impact their business.
Do have the obligation to accept payments using bitcoin even though they decorate
restaurant wall with a bitcoin sticker, if indeed they have concluded a franchise agreement and paid to place an advertisement on the wall, it means they have no responsibility for accepting payments using bitcoins. Bitcoin adoption has indeed been running so rapidly in various countries, but not all places accept payments using bitcoin.
You offer dinner together with restaurant management, I assume you intend to teach them to accept bitcoin payments, I don't think that will work easily and will not change the way payments are made in the restaurant. If a bitcoin campaign has graced the walls of their restaurant, it's highly unlikely they don't know how.