In New York City you need to leave a tip otherwise the delivery worker won't pick up the order (found this out when trying to tip in cash one time). Tips don't seem to be optional when it comes to delivery in urban areas.
I've a feeling the delivery fee will increase, customers will continue to tip otherwise they won't receive their food, and overall the price of delivery will increase and the number of customers willing to foot the cost will lower.
I live in NYC, but I've always tipped. I thought that they couldn't see the tip until after. Factoring that in, I read it the same way as you. That said, I order food less than once a month simply because I find it such a rip off (already).
I wonder whether Fresh Direct / grocery delivery prices will go up as well.
I've a feeling the delivery fee will increase, customers will continue to tip otherwise they won't receive their food, and overall the price of delivery will increase and the number of customers willing to foot the cost will lower.