At least once a week, my mail isn't delivered until after 6:00 pm; unacceptable for a freelancer like me who gets checks from clients in the mail.
I recently sent a magazine I sold via eBay in a regular 9" X 12" envelope. The buyer complained that it arrived in horrible shape, resulting in neutral feedback, which isn't as desirable as positive feedback.
A client's 1099 arrived 2 weeks after they sent it; I wound up asking them to send it digitally as a PDF. Sigh.
And the U.S. Postal Service wonders why it is teetering on the brink of bankruptcy...