> Should they be obligated to open and censor your mail?

they are. they're not obligated to go through every package but they are absolutely obligated to turn over packages to law enforcement, and they do, and law enforcement will one hundred percent open and go through your mail. and if they find something you shouldn't have they will dress up as a mail carrier to deliver it to you and then detain you!

I'm not sure what point you're trying to make exactly but this is a losing battle

If the government wants to read your mail, they need a warrant. And then it's the government doing it, not a private company, and you have a right to a trial and to see the evidence presented against you etc. etc., which is why it shouldn't be put on a private company who isn't going to do any of that.