I don't mind paying whatever things and services should cost, but this system is insane, especially the percentage consideration. Are expensive foods heavier? Do they require more skill to carry? Did you get special training to bring me my foie gras that you didn't need to bring me a hot dog?
My gripe with the whole tipping system is what designates who should get tipped and who shouldn't? By default I am supposed to tip my waiter even though they don't particularly provide me any unique service I couldn't do myself. I can take my own order, pick up my own food, fill up my own water. The job requires very little skill, I would know I used to work in a nice restaurant. Delivery guy I have no problem tipping because they're saving me time/effort. Do I tip my dentist? When he does an awesome job on my root canal and saves my tooth? Or the guy who does my oil change, when the 30 minutes oil change takes 28 minutes...? I mean what designates who should get tips? It's certainly not pay because in California there's something called minimum wage and no one can work for less than that, unlike in some other states. In those states it makes sense for tipping because it subsidizes the shitty wages those workers are paid. But in California it doesn't really make any sense, those restaurant workers are making stupid amounts of money for minimum amount of work especially if you're at some expensive restaurant. I have been to Japan where there is no tipping, it's frowned upon and yet I get fucking amazing service there. I was blown away, this person has zero incentive to perform well yet they're crushing it. Go anywhere in Japan from the shitty 24 hour convenience store, McDonalds, Starbucks, fancy sushi restaurant you'll get the same high quality customer services everywhere.
Manager sounds like a dick. Delivery guys should always keep their own tips because typically they're driving their own vehicle, pay their own gas and insurance, car wear/tear/maintenance, potential danger and they have to drive around deal with a bunch of dumbasses like idiot stoners trying to pay you in weed. Which would be great if I was a degenerate loser living off my parents money but shit monica I got bills to pay.
If the manager wants you to split your delivery tips ask those guys to help pay for your gas, mileage, oil changes, tuneups, new tires, brakes, insurance, etc., otherwise fuck that you're better off driving for Uber or Lyft.