I agree with privatizing USPS. The customer service may improve since I find the employees very rude at times. If at all possible, I go to the USPS outlets or use another service provider. I think the employees have the usual Government employee mentality as seen at many Government offices. They seem to forget who pays their wages.
" But the USPS has insufficient funding"
The USPS is an autonomous agency; it does not get funding from the general budget. They have to pay for their expenses with only the income they generate.
As for the comment about the delivery trucks, I doubt they are from the 80s as you speculate. That's over 30 years. But they do have them specially made for them and the design has not been changed much.
As for the workers' attitudes, well, they are Union. Why bother working when you can't get fired?
And the "physical plant" department (aka maintenance) is also Union. Paperwork up the wazoo and a lackluster attitude makes getting anything done a race with the turtle.
USPS is already semi-privatized.
The reason a lot of employees seem down and out is because they constantly incur the wrath of vengeful and angry customers who have little patience and lack basic manners.
speak with your postmaster regarding the situation.