My experience with the post office and my discussions with friends who are postal workers as well as friends who have problems with the US postal system is that the quality of the service varies by location. Some areas have a lot of problems, others do not. If you are stuck in an area that has problems, there isn't much you can do about it. There are endless stories about terrible things that happen and then there are heart warming stories about postal workers who go out of their way to help customers and correct errors. It sounds like you are in one of those unfortunate places where the service is not good, so you might UPS and FedEx would be the way to go.
Even though I am in an area with excellent service and I have friends within the system who have helped track lost items - I still recommend to clients that they use only FedEx and UPS for their envelopes. I use a franchise shipping store and in over 10 years, the owner has never had a lost package. A couple times there were significant delays, but the package always showed up. Even thought the USPS offers tracking, they still manage to lose things.
I agree that it would be nicer to speak with a live person in customer service at JetPens, but, I can see how it would be an expense to staff customer service reps. They would have to pass the cost on to the customers which would make the items more expensive and I believe they are trying to keep their prices pretty low. I have never had a problem with them. Most of my orders are for hard to find colors or for trying new products. The free shipping on orders over $25 is pretty attractive.