What the lecturer thinks about the turnout rate will depend a lot on the lecturer and their work environment. In many places teaching is not valued, whether explicitly or only implicitly (it can count very little towards pay/promotion/social-standing). So some lecturers simply do not care. Others will care, but may not know what the problem is or what to do about it, since many will have little or no training in how to teach.
Also, be aware that what students want and what student need are not necessarily the same thing. Just because you and your course-mates agree on what you don't like, that does not automatically mean you are right. In the end, most students will want their degree to be valuable more than fun.
My suggestion would be to propose a discussion on what the purpose of a lecture is, and what part it is intended to play in the learning process (and indeed what you are meant to be learning). This is often not discussed explicitly, since each person may feel the answer is set in stone, but in fact the answers in people's heads may be very different. It may be that just having such a discussion will get the lecturer thinking (which might not result in change within the time-span of your course, because change takes a lot of effort, and is also prone to being unpopular with students), and it may also show you a different side of the lectures that means you can make better use of them (which admittedly won't help the students that have already chosen to leave).
As an anecdote, every single one of my lectures consisted of the lecturer writing on the board, which we copied down (with some minor variations). The content was all abstract mathematics. Yet I never felt the need to label the lectures boring. A couple of my friends did consider one class boring, because the pace was too slow. But the lectures were what we expected, gave us what we needed, and covered some interesting topics (and others I was less interested in).