A reasonable tip ensures that someone will accept your order. Nobody is forced to go pick your food up.
I did a bunch of ride-a-longs with my buddy during COVID. Watching him decide which orders to accept was fascinating. There are lots of variables, and a reasonable tip was a requirement.
It basically boiled down to how much money per mile.
Some shady people will put a $20 at first, but then change it to $0 after the food is delivered – not based on bad or slow service, but because they are assholes. The $20 is to get a Dasher to accept the order quickly. Bait and switch.