The worst HCI

document.getElementById("UserName").focus();

This is the javascript that is the worst simple HCI that I had ever seen. When you try to login in any website, if the downloading of the page is completed while typing the password, then the above code puts the focus in the username, and the password comes in the username text box, and others can see the password. This is a very simple, and it happenes very frequently. But, except very few websites like gmail.com, orkut.com, most of the websites have this problem. Why websites won't take care of even simple HCI things like this?