Surrogacy and Inequality

When egalitarian liberals object to things like surrogate motherhood, I understand where they’re coming from even as I disagree. But what is one to make of something like Ramesh Ponnuru’s apparent egalitarian objections? Differential financial power is objectionable enough that it provides a grounds for banning certain kinds of consensual transactions, but it’s not sufficiently objectionable that we should actually do anything to try to eliminate or ameliorate it?