I find it very interesting that, according to my own brief observation, almost the opposite situation is happening in China.

In China the dominant food delivery platforms are ele.me and meituan. The food offered there are not marked-up so ridiculously compared to dining in.

As far as I understand, this is because

1. The demand is huge. People prefer food delivery, especially for lunch, to save time to either play mobile games, or squeeze more hours for work. Another reason is much more choices are available online than say within 10 minute commute.

2. Due to 1, food preparation is often moved to backstreet or upstairs where rent is significantly lower.

3. Due to 2, many sketchy food providers on the platforms are not actually restaurants. So, they don't have to bare the cost of regulation compliance like license or hygiene standards.