Probably because nobody's gotten sued for using the same banner yet. At the end of the day, this law has added a burden very few web site admins wanted; they don't want to understand a law to provide content on the Internet (especially when that was unnecessary only a few years ago, and especially when it isn't perceived as adding value to the user experience). I'm not surprised if people try and do the minimum legally necessary to comply with its ambiguity and pray they don't become the test case to resolve that ambiguity.