Delivery app tip culture is a fascinating rabbithole in and of itself. /r/doordash is a great repository of posts to look at. You can get a sense of expected order pricing/tip amounts/driving distances sufficient to compel a dasher to pick up your order. Much like with the restaurant industry you will notice that quite a few (I would say a majority of posters there) take issue not with Doordash but with the delivery recipient as the cause of their low earnings. Tips are the name of the game, and any fervor to change or push Doordash into changing their payment models are hushed by the collective din that laments "stingy customers".
Whether it was planned or a happy coincidence, that mentality is a sociocultural win for doordash as a company. The customer, who themselves can make no guarantees how much of that tip a driver will receive if paying digitally, is to bear the burden of blame more than the company that contracted that service to a driver when said driver feels underpaid. It feels me with a sense that's hard to describe. Disheartenment maybe? That new markets and services appear and the tipping culture we crafted for ourselves comes in with them, absolving some companies of paying market wages and sometimes shielding them from certain wage laws.
I wish we in the US could collectively agree that this culture of tipping is (imo) a net negative for everyone involved. But with an economy looking over an uncertain horizon, and the recent bottom-to-top wealth transfers facilitated by the chaos of covid, I think the simple act of throwing a few bucks to the service worker will remain the average American's daily act of "helping the little guy" regardless of how real that benefit truly is.
