Not saying that's the case for everyone, but you can't define "customer friendly" in a narrow way that conforms to your personal desires and assume that's that.
Also consider that if banks did have strong authentication around every purchase, there would be less of an incentive for banks or merchants to agree to roll over and eat the cost when there is fraud (and more ammunition for them against laws that require them to). No security/anti-fraud system is perfect, and something will always slip through; I wouldn't want to be a card holder stuck with a big bill because someone managed to clone/swap my SIM (for example) and make transactions using my card if I had no protection from that.