Italian bureaucracy is not difficult because it is complicated. Any individual step in it is simple. A form, a queue, a stamp.
It is difficult because it is sequential, and the sequence is unwritten.
Nothing in the system announces its own prerequisites. The Anagrafe does not publish a notice saying "do not come here until the Questura has processed you." The ASL does not warn you that your enrolment will fail without a residency certificate you have not yet applied for. Each office assumes you have already completed the office before it, and no office tells you which one that is.
So a completely reasonable person, holding a correct and complete set of documents, walks into the right building on the right day and is sent home. Not because anything was missing. Because it was too early.
Three examples of how this plays out, and I have seen all three happen to real people:
Anagrafe before the Permesso receipt. You go to register residency without the ricevuta from the Poste Italiane submission. You are refused and rebooked, typically two to four weeks out, and every downstream step slides with it.
ASL before the Anagrafe. You attempt to enrol in the national health system without a completed residency registration. Refused. You now have no Tessera Sanitaria and no assigned medico di base, in a country where you have just moved and know no doctors.
Bank before the Codice Fiscale. You attempt to open an account without your Codice Fiscale (Italian tax identification number) from the Agenzia delle Entrate (the Italian tax authority). Refused at the door. And without an Italian bank account, the utility contracts and the lease behind it cannot complete either.
None of these are exotic edge cases. They are the default outcome for a prepared person operating without a sequence.