Four mechanics, one reason.
Full menu, happy hours, deals and surplus look like four features. They are four answers to the same question.
The question is: why would somebody open this app tonight? Each mechanic answers it in a different situation, which is precisely why one alone would not be enough.
Full menu answers the ordinary evening — nothing special, but cheaper by default. Happy hours answer curiosity, because something unpredictable is live right now. Deals answer intent, when a merchant has built exactly the thing you wanted. Surplus answers timing, at the end of a day.
A single-mechanic marketplace only works on the nights that mechanic happens to fit.
Together they mean the app is worth opening on most evenings, and that frequency — not any individual discount — is what makes the marketplace hold together.
