The prices in the app are lower than if you actually order in store. Specials and coupons are only offered through the apps now. Actual store prices can be seen on the delivery apps or by just going to a store. You can't actually order online through McDonald's directly because they are trying to force the app on you.
But who actually wants the hassle of having an app for McD, BK, Subway, and other garbage where you're trading your data away, and giving everyday advertising space on your phone, for food that doesn't even taste good for a slight discount.