Her house is a historic Western restaurant, and the quality of taste doesn't change even if it is a bento, and there are a lot of repeat customers. Customers who couldn't buy because of the limited quantity burned with fighting spirit to try again at a later date.
Her family runs a traditional restaurant that serves up an array of taste sensations. The quality isn't diminished when packed into a bento box, hence the high volume of repeat customers. Customers who can't manage to secure one of the limited boxes come back and try again another day.