You know when one day you realize that every pair of your kids' pants are too short? And you get him some new ones, making sure to get the ones with drawstrings so you know they'll adjust small enough to fit his waist, even though he's average size and all the pants SHOULD fit him anyway but you know they won't because they are always made for someone with a much more rotund belly?
Yes, every single drawstring in the above photo is fake. There is something wrong with the world. So now your choices are either:
until you yank on the elastic and re-adjust it to make the pants as small as they need to be. Then you can re-button as your kid grows, so the pants grow with him: