Everyone knows the meme “The less a client pays you, the more difficult and demanding they are going to act.”
Now, I always remember my old analysis professor saying, “Anyone can point at graphs. To be an analyst, tell them why this happened and what can be done about it”.

Here goes: Why, and what to do if true?
1) Don’t see the value of what you do – explain through gestures, stories, or figures
2) Can’t afford your work – offer payment terms or move on.
3) Don’t have experience buying expertise – manage expectations, dress extra nicely, and don’t let minimizing language go unchallenged. Let them know you are a type of “hireling” that’s a whole different deal than the commoditized service providers they are used to.
4) Need to be seen as tough negotiators – offer them a deal that includes them looking great, with actual little monetary change.
5) Keeping an eye on the bargain-level provider – stop giving discounts, be clear on the reason for the bargain, and stand firm on boundaries.
6) They want one thing, but need something else – charge for an analysis, then get them to either change specs based on data or run away. No one wins in this kind of conflict.
There is no universal truth about why clients don’t want to treat you like colleagues. Still, that list rarely lets me down in my pre-negotiation workshops. If you have something to add to the list, please share it.