6 days and still not there

why would anyone want to mail priority mail when it takes 8 days for a domeatic delivery. I sent an letter my normal mail to Tarpon Springs, FL and it took 4 days. I paid 8.75 for priority mail to Marco Island,FL and after 6 days it still hasn't arrived. I also sent an important letter priority mail to DesMoines, IO, tracking said it arrived on Nov. 23 - sorry but it still hasn.t arrived! Just try to contact anybody via phone at the post and you will go through endless recordings untill you give up in despair