I think the simplest way to tell is if the app requires you to tip before or after the order has been placed.

I've read in other HN threads that Uber Eats tip policy is what we as customers expect, but don't take my word for it.

It would be just as easy to implement a process where a tip after-the-fact still reduces the "employee"'s normal pay.. Do just mean, in practice, that's not the way it's normally implemented?

You're right I didn't consider them making it up on the backend somehow. I still believe that forcing a "pre-tip" is a clear indication of something sketchy going on. I can't think of any other valid reason for forcing it.

This driver isn’t paid until after the delivery anyway, so that shouldn’t be a factor.

When deciding to tip before or after the service is rendered, these are the considerations likely to be weighed:

Pros for asking for tips before delivery:

1. Tips are more likely (eliminates scenario where user ignores the app after the delivery and never sees request to tip).

2. Tips are larger (user may perceive that the tip will influence the quality of service).

Cons:

1. Tip option increases perceived cost of order (or guilt if not tipping), so this additional step reduces number of completed orders.

With the DoorDash policy this article is referencing, where the company probably only makes a profit if you tip, it makes sense to ask for tips upfront. For the Uber/Lyft policy where tips are more for the benefit of the driver, it makes sense to tip after the ride.