alt Hacker NewsDelivery was financially viable for decades before delivery apps. That's why restaurants did it on their own. What's not financially viable is VCs investing billions to create global oligopolies, and and then expecting outsized returns on that investment.
At the same time you have processes like increasing suburbanization and development of even more car-centric infrastructure, which makes houses and restaurants even further from each other, and makes cheaper delivery vehicles like motorbikes infeasible.
All of that is true. However, I think you don't account enough for the differences in the current and previous delivery models in delivery's viability. The old model was "drivers employed or contracted to individual restaurants, with fairly strict distance limits." Today's apps let you order from arbitrary restaurants to arbitrary delivery addresses. The other factors make the situation worse, but just this one is enough to turn a viable model into one that can't be profitable without someone involved getting scammed.