3-way bulbs are obviously a particular US thing.

European Edison base sockets are built differently, they don't have live threads, instead they're built with two bottom terminals. The actual thread is isolated from the shell by a plastic ring. Never seen one of those fail, the only typical problem: overheated cord, PVC gases out creating acidic smoke, terminals corrode.
Here's a pic:
[Linked Image from electrical-photos.com]

The outer shell is also considerably sturdier than its US counterpart.