Registered International Mail (Somewhat Off-Topic)

This is a little off topic, as it really doesn't pertain to collecting stamps. But I am just curious.

So, here's some background. I focus my collecting on Yugoslavia, and all the republics that were once part of Yugoslavia. As such, I tend to make the majority of my purchases (via delCampe) from sellers in Serbia, Croatia and Bosnia. Because of my lack of faith in the postal authorities of these nations, I almost always pay the extra money to have packages sent registered mail (unlike the outrageous $11.50 the USPS charges on top of postage, I can have a small packet of up to 100 stamps shipped, registered, for about 4.50 euro - about US$6.50) I have never had a registered package lost, yet (knock on wood).

Anyway, beginning earlier this year, I have noticed a new trend, and it bothers me. So far, this year, I have received 5 packages (4 from Serbia, 1 from Bosnia), all sent registered mail (with the proper stickers attached to envelope) that were dropped in my mail box, without me signing for them. I have always had to sign for registered mail, and the signature card always has one of the bar-code labels removed from the main sticker on the envelope.

My understanding is that it is the USPS responsibility to put the label on the signature card and only deliver it when the card is signed. (am I correct?) And if I am correct, is this done at a local level, or upon entering the US (whatever major postal terminal receives mail from eastern Europe?) should I direct my concerns to the local Post Master? or go to higher authorities? or just let it go?

just looking for some input.

The mail from SERBIA (mainly) and another Slovenia, Croatia, Macedonia will go out from country with registered, tracked mail, and if sender provide You with number, than You can see it and follow on-line.
I too, have no lost mail this way.
Mail from Macedonia - same, again if You wish to see it on-line, You will need information about "R" number.
Bosnia (all three part), I have bad experience just with Muslim part (Sarajevo), because all mail from there will go first to Turkey warehouse. This caused some damaged mail, and few lost, even that I have this tracking number!

Now, as You know, most postal Companies are privatized, or partially sold to contractors.
Here - local post offices are in hands of contractors and they even don't dare to send piece of notice that "R" mail is there!
If I don't know tracking number, and check on-line, probably some mail will be lost!

shown: mail from Bosnia, canceled in Turkey, stamped by warehouse workers, signature of same person (actually three different person that check this mail).