I tip 20% which i think is fair as a family of four our orders range from $50 to $100. Well the last two times in a row our drinks do not arrive. Once an order from Red Robin never arrived. The resturants all say the complete orders were sent out. It makes me want to tip after I review the order or take the time and go pick up the order. On this occasion today as I walking to get my order as i hear the driver say "I am bad, I see it reads back door" I wave at him to come back as I can clearly see no drinks with the order. My thoughts are these drivers can rip off customers and know nothing will happen to them.