Lordy, a tip of more than 20% puts almost any restaurant out of my price range. Pretty much leaves fast food.
I do think that those problems are caused by servers 90% of the time, because they are server mistakes. Only in a restaurant that is truly a catastrophic sinking ship will you find a cook that, despite making the same menu for hours night after night, doesn't know how to make the food correctly. BOH mistakes that I find common are food that clearly hasn't been held correctly, hamfisted use of flavors, sloppy execution, mystery flavors from cross contamination of spices and what not, or the odd ingredient, like a surprise bit of pork in your vegetable fried rice. Mistakes like incorrect orders, cold steaks, hairs on a plate, food coming out in nonsensical order, etc...that's your waiter's job!