[ahti]

So they tear up the plastic, remove the original seal, open the box, close and reseal?

Correct.

What about new iphones, that come without plastic, but with paper tear up.. do they really tear it up and replace with new, original?

They have the paper pull tab seals on hand.

Upon checking Its contents, It's resealed as per the manufacturer's state.

Somehow I doubt all the stores would do this. Or atleast all the countries. Maybe not all amazons do that?

Never assume.

Both online and In-store check sealed box returns.

Maybe they use x-ray instead of opening?

As stated above.

What about ebay private shops or sellers?
Different items then apple, maybe less known to be frauded with?
What about lower valued items from amazon, thats not worth opening and checking? Like example 10x items thats worth 100e