Having retired from the U. S. Postal Service in 2004 after 44 years, and with about 35 of those years accepting (and rejecting

) parcels for mailing from the public in five different Postal facilities in four different parts of the country...I can assure you, there
IS no difference in the way mail is handled by
ANY of the 'big three' (USPS-UPS-FEDEX!)
I could tell you
horror stories about 'poor' packing (by customers) of things to be mailed, that you wouldn't believe!
AUTOMATION is the destroyer of packages and parcels, and
not the people handling the mail! In all those years with the post office, I
never witnessed any postal employee 'deliberately' mishandle mail that was marked fragile, but I have observed machinery flinging, dropping, rolling, etc. items in the mail stream with utterly no regard for the contents...how could it, it's just machines?
With the volume of mail handled by USPS-UPS-FEDEX, etc there would be no way to handle it
without automation machinery, so the only safeguard against breakage or damage of the contents, is ADEQUATE PACKING! I've often wondered if people mailing a package, actually believe that someone walks around carefully carrying their package between Seattle and Miami! Right!
A good 'rule of thumb' for mailing something delicate or fragile (like a classical guitar) is: Pack it so you would not feel 'uncomfortable' about holding the box shoulder high, and then DROPPING IT onto a concrete floor!

And no, I am not joking! If it's packed correctly, it will be just fine, and will get through it's journey okay. I think also, rather than marking something FRAGILE, is to mark it "HANDLE LIKE EGGS!"
I'm not trying to vilify delivery companies altogether, but am merely indicating that the general public 'has no clue', as to the sheer volume of items being handled and delivered, and the fact that the people doing this are under such pressure (and often unrealistic 'standards' of performance) that they have no time to show 'special care' for items poorly packed! Observe the average UPS driver-deliverer, and you will notice that they are actually
running to your door or porch! Show me a
fat UPS employee, and I'll show you a manager/supervisor!
David