I cannot stand USPS service and pretty much refuse to order from companies that only offer them as a shipping option. Couple of things I've dealt with just this year:
-Ordered expensive print that had a giant yellow stickers saying "DO NOT BEND!" Find it folded up and crammed into my mailbox.
-Had very expensive camera equipment being shipped to me. Specifically request "Signature Required" but they left on my porch for anyone to steal (had their tracking been worth a damn I would have been home to receive it).
-They put a business check for several thousand dollars in a neighboring businesses mailbox (I also get their mail constantly despite it being properly addressed).
-Wife ordered fancy knitting needles and some sweatshirt defuzzer thingy. Package looks like it had been run over and sure enough the knitting needles were all bent and the defuzzer thingy was in a million peices.
-For the last 3 days (X-Mas Eve, yesterday and today) their tracking has said my stainless steel dryhoppers that were ordered for me for X-Mas were "out for delivery." Still haven't shown up yet.
In every single case they have literally done NOTHING to make up for it, not even offering up an apology. Thankfully when it came to the damaged items the companies that we ordered from were more than happy to replace the damaged items but it is ridiculous that those companies have to foot the bill for the USPS incompetency.
I should also note that at least for my house, the regular mailman is a nice dude and we chat it up all the time so it isn't like my mailman hates me. For my business, I don't know what the hell that persons problem is but after multiple complaints about them mixing up our mail with other businesses it still happens constantly.
Your issues all boil down to the individual carrier/local office. That can be a problem with any service. Around here the FedEx carriers and local depot are despicable and I will do anything to avoid them. At my previous apartment the local PO and mail carrier were awful and FedEx and UPS weren't too bad. It really boils down to the actual people that staff the local offices and do the actual delivering. If you are having issues with your fragile shipments being handled poorly by your mail carrier you need to call your local Post Office and speak to someone about it. If they don't address it you need to go higher up the chain.