The middle and lower class folks on my route always tipped something. The upper middle class tipped well. The worst was the richest person on my route (and, arguably the richest in town at that time). She wouldn't even pay me for the papers. It got to the point where she had to pay the office directly and they'd let me know whether to deliver. Never once got a tip from here. I picked up a second, adjacent route, and they were mostly upper middle and upper class business owners. They tipped well. Most had built their businesses from the ground up or worked in them and inherited them and did well by their customers and employees.
Learned that the hard way. Hiked five miles across town to sell candy bars for a school fundraiser, in the rich part of town. Discovered that rich people stay rich by sitting on their wallet !