Have things seriously gotten this bad, that restaurant workers are shaking down delivery drivers for extra cash? So much for solidarity with fellow workers.
Tips are for service, and selling food is not a service. At a restaurant, tips are for the waitstaff that brings your food and cleans up after you. Everything else is people hustling for extra cash. And yes we all like extra cash, but that doesn't make one entitled to it by putting a cup on the counter.
(Delivery drivers bringing food to your house, and drinks at a bar are two separate categories of service where tipping is legitimately expected. Although now that I think about it, maybe that second category was just the beginning of people getting suckered).