I always tip delivery guys too but I kinda don't like that. I do because they don't get paid as much and I feel like I'm paying for the services rendered. But at the same time, it feels a little 'unjust' to give the same tip to a guy who just handed me some food, took my money, and went on his way as I would to a waitor or waitress who checked on me several times, refilled my drinks, took my order, etc.
You are probably not the only one feeling this way, and that would explain some of the horrible tips we receive and some times no tip at all. But if you take the time to think about it, when you go to a restaurant with friends, let's say a table of 4 and you all eat for let's say 30$ each (affordable place). That's 120$ for the table and the waitress gets 15% so that's 18$ for serving your table. She comes by a few times, and refills the drinks and all but overall during the entire evening you are there she's at your table for what? 5 to 10 minutes total? For people doing delivery, we start by preparing your order, that takes about 5 minutes making sure that nothing is missing and getting it to the car. Then we drive to your place. On average it's about 5 to 10 minutes drive on the road. Then we go to your door and hand you the food and take the payment, let's say 3 minutes more. So for your 20$ order (ok sometimes it's much more) we we work 13 to 20 minutes. During a super busy evening we can do 5 delivery max in an hour. So at best we spend a minumum of 12 minutes serving each client. And that waitress doesn't have a risk of accident, doesn't have to pay for gas, doesn't put wear on her car and so on. I am Lucky to have a vehicle provided by the restaurant I work at which is branded to our chain but it's really the exception in the delivery job. So while I know many people feel like you do, I really don't think that mentality has any roots in reality.
Certainly not a criticism of the delivery guys; but a tip is supposed to be a gratuity paid at the end of receiving adequate service. The delivery guy I only see for a couple of seconds!
Really that's a criticism of the system in general. I think they ought to just get paid. Even if they did make minimum wage, there's wear and tear on the car and fuel expenses. (One of the biggest mistakes I think young people working delivery jobs make is assuming they just have to pay for the gas, forgetting the depreciation, wear and tear, and maintenance on the vehicle. When I travel for work I am paid $0.52 a mile per my odometer plus expenses; which is the Federal mileage rate, a rate determined based on what the 'average' car actually COSTS to drive, beyond just the fuel used!) I love how a lot of places charge a 'delivery fee' and make it a point to tell you to still tip the driver because the delivery fee is not given to them. What exactly do they need a delivery fee for then?
I agree with you the tip system has it's limitations. Many places around the world don't use it. Personally I think it forces people to provide a better service so I think it's a good thing. The problem comes when people take advantage of the fact it's not mendatory and don't follow the rules. Here in Canada everything is based on the fact people will leave a 15% tip. We are taxed as if we receive that. So when people don't tip or are super cheap, we actually pay for the service. If tips did not exist. the price of the service/merchandise would be higher to reflect the higher cost of doing business, so in the end the Customer would pay roughtly the same but the person providing the service would have less of an insentive to give a good service. So as I said before, I think the system is good, even with the people abusing it.
Like I said, I still tip the delivery guy. I just always felt that weird. Kind of unjust to 'traditional' servers yet at the same time, they are working hard for me, and are not getting paid an amount relative to the work they put forth!
Still was a very bad tip, should have been more on the 30-40$ range but I found it so funny that I was happier than if I had received the proper tip LOL That just made my day 
