It's definitely more complicated than that. I travel a lot, sometimes to places where borders are dotted lines, cities use a script I can't read, but every hill is "charlie-5" or somesutch... VPNs, public terminals, government networks on .mil.<country> domains, etc.

I have been quite impressed with the improvement they've made in the last year or so regarding these locks. It's probably a sudden change when you've been more predictable before that gets flagged.

Only trouble I sometimes run into is Google Search (or Books?) locking me out with increasingly difficult captchas if you keep running searches for 18 hours straight.