Here here on the construction standards irony. I've never witnessed so many builders hacking off and subsequently rebuilding bits of buildings as I did whilst living in Italy. Incessant drilling and banging. Didn't point to particularly high standards of construction in my experience.
I've heard it said that the hot / cold taps are a legacy of our very old plumbing. Probably connected to what a pp said about safe drinking water.
Don't get the big deal about ID cards. Genuinely can't see what the fuss is about.
Carpets are because it's cold here. We clean them with vacuum cleaners. Me personally I prefer wood floors but carpet is popular for that reason.
My own weird observations about Italy:
Insistence that I can't have a capucinno in the afternoon. Or indeed any time after about 10am.
People sweating in long sleeves and socks in April and May because summer hasn't officially begun, then a wholesale change to shorts, sandals etc on June 1st, at which time it is also acceptable to swim in the sea or sit on the beach. See September 1st for the reverse.
Dogs barking all night, and I mean ALL night long. Do they not drive the owners insane? Are they beloved pets or guard dogs? If the former, why so neglected? If the latter, why is no-one investigating?
The staring! I know this one is a culture clash, neither side is particularly right, but we are taught as British kids that it's rude to stare. It's deeply ingrained and hard to shake off.