It is not a bug. It looks only that you have not understood the difference between detecting/capturing an event and attaching an event.
var eventType = e.type;
This anonymous will not act as an inner function, it will simply capture the generic event on the whole element , so that the target will be in fact the element itself or any of it's child nodes, it depends on which of them supports the event at a certain moment. To understand better, take a look at a simple example, using the onclick event:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta http-equiv="Content-Style-Type" content="text/css">
border:1px solid #ff0000;
var target = (e && e.target) || (event && event.srcElement);
<div id="container" onclick="check(event)">
<div id="firstID">click here the first div</div>
<div id="secondID">click here the second div</div>
click here the container
That not means I have attached an onclick event to all the child nodes of the container node. I have simply captured the event onclick itself, and whenever that event is fired inside the container div, it will show me which is the target upon I have performed the click. The target might be the container itself or any of the child nodes divs, depending on where I do the click.