There are plenty of these restaurants all around the world, they’re just not cheap. Poke bowls and salads and Sweetgreen are very popular, go to any downtown anywhere. But where McDonald’s uses shelf-stable, globally sourcable bulk materials, these places are the opposite. Both Coke and salads are mostly water, but the Coke ships as a concentrate and the salad ships whole. You can sign one contract and get a regular, reliable delivery of Coke to your stores in Houston, Anchorage and everywhere between; good luck doing that with salad. There also aren’t any great huge-markup upsells with healthy foods; the closest thing is guac, which costs a ton, meanwhile McDonalds can upsell you on fries or coke (which are basically free!) There’s the trend factor: Baja Blast is catchy and you can rotate it out for another neon soda in a week, how do you do that with arugula? Artificial ingredients provide more of a moat/proprietary edge; it is legally and practically trivial to copy a healthy sandwich. Healthy foods are more difficult to eat while walking or driving, so you need more seating. Then there’s the prep time, the addictive factor, calorie density…