Food delivery has existed for a long time at much lower cost than today. What recent developments has made it so much less efficient?
When every restsurant delivers separately, and the delivery agent isn't based at that restaurant, the economy of scale vanishes.
The scam was getting them to use their own vehicle without mileage fees for depreciation. But even that’s gone now with lots of pizza places having a fleet of delivery vehicles for the drivers.
To your snarky meta-point, yes, having people learn the market rates for labor is a good lesson. It’s really good for teenagers who don’t actually need the money because it’s about the lowest risk hands-on way to figure out that life is harsh to people who have limited skills for where society pours its money.