This is an old chestnut, but fresh ideas would be welcome.

I'm teaching English for academic purposes to pre-intermediate students. They want to do authentic readings, advanced level vocab, exam practice and other stuff they believe necessary for exams they won't be taking for a year or more.

I think that approach is a bad idea. They haven't even got the basic tenses yet. Correct use of the present perfect? The difference between will and going to? They've no idea, but seem to think that learning it is a waste of time because it's not "related to the exam".

Has anybody else encountered this attitude, and if so, how did you handle it?

I agree with you, that students need Engish-English before they need business English, medical English, legal English ... It takes a longer view than most places are willing to go for. They want instant results for tests and can't spend the time building language competence. They take the short view of lets get down just enough to pass the test, which in the end usually leads to near zero retension a year later and an inability to actually use the language they are memorizing.

I believe that if you are a competent language speaker and competent professional all you need is the vocab. So, I think if you aren't a competent language speaker, that should be your first goal. After all, it's the regular daily conversation that builds good business relations or professional raport. Most meetings or professional situations will be mediated by interpretors anyway. So, it's the ability to converse by the water cooler or at a dinner party that's going to help your company in international business situations.

I teach nursing college students and part-time at a company. Both wanted ESP lessons but I convinced them that a general English conversation textbook would serve them better.

I supplement the textbooks with my own materials to make a connection between what we are learning in the textbook and how that can be applied to medical or business situations. Sometimes I just make reference to how it could be applied. Sometimes I ask them how they could use langauge like what we're studying. Other times, I just alter the conversations a bit on the board.

For example, the first unit for my lowest level medical class is introducing yourself and introducing two people to each other. The text book conversation goes something like this:
A: Sara, this is Tom. He's in our math class.
____ Tom, this is Sara. She's from Argentina.
B: Hi, Sara. Nice to meet you.
C: Nice to meet you, too, Tom.

I had them change the names to Dr. XYZ and Nurse XYZ. Then add a little information like 'He's from Saku Hospital' or 'He works in cardiology.'
A: Dr. Sanchez, this is Nurse Miller. She's from HE General Hospital.
____ Nurse Miller, this is Dr. Sanchez. He works in the E.R.
B: Nice to meet you, Dr. Sanchez.
C: Nice to meet you, too, Nurse Miller.

Everyone seems to be happy with that, but I think the key is showing them how that simple langauge that they really need can be applied to the situation they will be in. Then for the students it makes sense to be studying this basic material.

Basic level ESP materials like that might be a good market for materials writers to look to. I know I'd snatch up some remedial ESP medical texts if i could find them.

Like any learning, student goals are a key ingredient. If they do just want to pass the test and have no use for what they are learning beyond that then ... maybe you are trapped. As Mark said if you can convince them that learning English English first is an important step then you are able to give them a much better product that will last, and you will get a better sense of fulfillment.
Do they intend using their English beyond the class and test?
Here in Japan so much learning is exam focussed that it is really difficult to break teachers out of the mold. The benefits of teaching other ways are not necesarily evident soon enough in the half term tests, because they don`t test the things we have learnt, but measure some other rote learning. One of the teachers here confessed that she had only done lots of speaking and listening things and not yet started them in reading and writing as normally is the case. They do however have better ability than many of the third graders when it comes to having basic english conversations. I believe they will benefit so much more next year from the way she has done it this year

When I teach Geography I want students to get a feel for how a Geographer percieves the world and to develop skills to that end, then I teach the material that will be examined.