Not only is it cheaper to use Ritual. The rewards mean free food.
My office is huge into Ritual, it was used daily. The group ordering makes it way easier than "grab me a burger and I'll Venmo you". You can fully customize your own order without bothering your teammate with "no pickles, extra cheese please". You then pay on your own, so no one has to keep track of splitting bills and IOUs. A small bonus is that each individual order is packaged separately and clearly labelled so that you don't have to fish out items and work out whose is whose.
You can definitely achieve the same thing without Ritual, but the app takes care of all the pain points and pays you in rewards to use it, so why not?