&gt; Why should it be impossible for a third-party package to just create &#x2F;opt?<p>It is not impossible, obviously, but &#x2F;opt and such should come from the operating system&#x27;s vendor, and the vendor should be the only one to decide which filesystem permissions to provide: 0755? root:bin or root:sys? root:root? bin:bin? The vendor should decide that, since a vendor is supposed to know their operating system best.<p><i>Third parties might not agree, or even decide correctly for that operating system</i>.<p>This is system engineering and architecture, something which beside operating system vendors, software vendors do not have a clue about in the slightest.