It's becoming a common thing. I first saw it about a year or two ago, can't remember exactly, and this past year I'm seeing it a lot more. I assumed that as the UPS and FedEx folks got bigger they found it more difficult and expensive to perform that last step of actually delivering to the door. But like you, I see a UPS truck in my neighborhood almost every weekday (some neighbors work from home), so it's obviously not a system they've fine tuned. It does make sense for those routes in rural or other areas with few deliveries per square mile to have the folks who have to drive by six days a week anyway do the final delivery. At the same time, the USPS welcomes the additional revenue. In fact, around my area the USPS actually makes package deliveries on Sundays to generate more revenue.
I also don't like the fact that the final leg of the journey isn't tracked, and that the process usually adds a day or two to the delivery time, but since I always opt for the free shipping I guess I can't gripe too much. Now if they started doing that to stuff when I paid extra for premium shipping, I would be ticked. On a positive note, my local mail carrier is excellent and he always delivers the package to the door and rings the bell. The UPS guy on the other hand is too lazy to climb the two steps on my porch and walk over to the front door to push the doorbell button.
Jerry