Except unlike here in NA, the cost of a delivered meal in China is often times less than their in-restaurant equivalent. The delivery platforms there are still offering large discounts, and it's not only for new users.
For example is common to see restaurants offering, 15 rmb off for orders over 50 rmb.
(1) the restaurant has limited sit down space and chef time during peak periods;
(2) eating times in China are highly regimented (office lunch hour dominates);
(3) delivery customers by default can tolerate higher volatility in meal completion schedule;
(4) the actual cost to the restaurant for a 50RMB meal outside of the the limited sit down space represented by high rental costs and the chef's salary (already paid by peak hour sit-down customers) is negligible, often under 10RMB including ingredients, cooking energy and packaging;
(5) delivery platforms are battling for market share.
In short, the primary issue running a conventional restaurant is limited temporal and spatial bandwidth to serve customers. Delivery takes advantage of resources already spent toward the primary issues, so can be substantially discounted without loss.
For example is common to see restaurants offering, 15 rmb off for orders over 50 rmb.