It doesn't require much capital, doesn't seem very regulated and needs no deeply specialised skills to get started. No franchise. No middleman or supplier lock-in. No fixed rental payments.
Easy to pull in friends & family labour if you need to scale, and if you miss restocking it's no biggie. Nobody yelling at you. Flexible hours. Rarely have to talk to people except about new sites.
Actually not that easy to think of things with all those properties.