We also do not know what UPS is charging Amazon. Bezos speaks to shipping at every board meeting and how he is working at driving costs down. Plus, as we get more of that resi volume, our actual cost to deliver it has to go down. My route typically has 150ish stops. That is generally an 8.5-9 hour day. I have had a pile of days with 180 stops and done that in a relatively easy 9 hour day. Yesterday, I had 150 and barely had 8 hours. I had several times when I parked and walked off 4 stops. I am also seeing many more resi stops with more than 2 pieces per stop. That also boosts efficiency.
It would be interesting to know how many pieces it takes per resi stop to make it profitable.
edited to add... On my route, I start the day with businesses. Even after going to CIR, I rarely have more than 28 stops done by the end of my 2nd on road hour. My resi neighborhoods are 20-35 stops/hour. Every day, I have at least 1 30 stop hour, sometimes 2.