You're over-simplifying a bit. Public WiFi is a bit more risky, though, because the barrier to entry for sniffing last-mile infrastructure is so low that anyone

You're over-simplifying a bit. Public WiFi is a bit more risky, though, because the barrier to entry for sniffing last-mile infrastructure is so low that anyone can do it. At my home and office you have to contend with WPA2-Enterprise (it's easy to set up at home, so I did). You'd need to get hard-wired access to my home, and pull some ARP trickery to sniff my last-mile infrastructure. We have 802.1x on the Ethernet ports at the office, so no dice there. You're right, to a point. And the effective response is to make sure you're always protected as well as you can, instead of going into a "shields up!" situation only when your perceived risk is higher.