Maybe the issue isn't that the average instructor is using the position to build time, but that they haven't been formerly taught to teach? School teachers have to go on courses to learn how to teach. I don't know how far the FI course goes on this, but it is fairly obvious that they haven't been taught how to impart knowledge to others in my opinion. You are relying on experience, and personality to win through I think.
The instructors I have had have been great, and I think that maybe that is because they are of the same (younger
) generation as me and so the sense of humour, and banter are very similar, and as long as you can give as good as you get (and break through that attitude of "how privileged you must be sitting next to me") then you can get on very well.
The other thing is that if you don't get on with your instructor, don't think they are giving you the best tuition, being a bit of a prat, not very good at teaching, then you can always get a new one (or a new school). They'll soon get the message.