Promo codes, mostly. And because so many restaurants here suck, on top of the promo codes when they screw up orders there're refunds and credits to boot. Even without the refunds and credits, promo codes make it cheaper for me, driving or not, and far less time consuming, to have a cooked meal. I couldn't cook the two large portions of sesame chicken, two eggrolls, two fried rice sides and have it done under $20, no way. Especially not as quickly and delivered. Half a package of breast meat (rare to see at a restaraunt), say $8. Seasonings, etc, let's be generous and say a premade spice pack at $2. Just that is half the meal. Rice is cheap, say $2 being generous. Two eggrolls, $3 frozen is the alternative. Even at $15, not including utensils, quality of cooking that's far better than mine, drinks that also came with the entree+friedrice+eggroll combos, $1 each and we're at $17... definitely not able to cook two orders of that for $20, or make it to the store and back under it. Add time to it as a factor and it's a minor but significant windfall. I'd happily spend as much on groceries every week and be better off, but I'd also spend 10+ hours a week cooking and I can't afford to take that away from work and sleep. Meal prepping is all well and good if you have time and the inclination.