In addition to what everyone else said there are big regional effects: in North America cardholders have often never seen 3D Secure before, they don't know their passwords, and issuers don't care enough to make their authentication pages usable.
But in France and the UK it's pretty standard; cardholders are used to it, and issuers make an effort to decide whether it's worth requiring authentication.
But in France and the UK it's pretty standard; cardholders are used to it, and issuers make an effort to decide whether it's worth requiring authentication.