What could be incentives for publishers to waive fees for reusing figures? I'm in charge to obtain permissions to reuse figures from previous publications for our future work. Our publisher is a STM-signatory so for most journals there is little problem as their publisher are also STM-signatories and therefore allow to reuse up to three figures free of charge.

Other publishers request substantial fees which are sometimes waived when our head editor gets involved and states that the purpose of our publication is purely academic (though it is published for a profit by our publisher).

Sometimes even that fails and there seems to be no other way than paying the fee or not using the figure. We don't have a budget for this though.

My question is, are there any other non-monetary incentives for publishers to allow the reuse of a figure? I'm thinking of appealing to their "academic consciousness" to help to contribute to scientific advancement or possibly include a line in the figure caption: "With very kind permission from PublisherX" (is latter a common approach or desirable for a publisher)?
I've never had a problem getting permission to use a figure with proper citation – ideally such a usage drives traffic back to the original article / source too.  So that's one incentive right there.  Be sure to let them know you will send traffic / credit back and ask how they want to be cited and / or linked.

But authors ordinarily do not really expect to lose control over their IP, so authors would probably avoid such publishers if they found out that a journal "jailed" their figures. This is obviously a stick not a carrot, maybe saying something like "I think the authors would be very disappointed to find out if they have been disadvantaged by publishing with you, it might discourage them working with you in the future."