But it's important to be clear on precisely what the complaint is against. It is not that large costs are being imposed on the wealthy, or anything so object-centered as that. (There's nothing inviolate about the advantages held by the most fortunate, and nothing intrinsically problematic about redistributing these advantages.) Systematic redistribution is just fine. What's problematic, to my mind, is the very act of demanding action from another, and the psychological burden this imposes.
Humans have limited executive cognitive control or 'willpower' (cf. the psychological literature on ego-depletion). Decision-making and conscious action is draining. It's hard work. The immediate concerns of everyday life can be burdensome enough without adding all the world's ills to one's plate. Again, so long as one is leading a basically decent life, it just doesn't seem reasonable to condemn them or demand that they attend to more pressing concerns elsewhere. Most people have more than enough to attend to already!
It's worth noting the contingency of this concern. If we can make it cognitively easier for people to do good, then we could reasonably expect more from them. Habitual behaviours are less demanding, for example. Best of all would be to free them of the burden entirely: replace opt-in schemes with opt-out ones, automate charitable redistribution via taxation, etc. Don't demand, just take. (Liberty concerns may be mitigated by the opportunity to exercise one's agency in the deliberative-democratic processes behind this policy decision.)
My account of the demandingness objection thus leads to the rejection of Liam Murphy's constraint against imposing unrequired sacrifice. Brian Berkey introduces it:
The intuitive idea behind such a constraint is that if a person is not herself required to make a sacrifice, then it would be inappropriate for others to force her to make it.
This only makes sense on an object-centered view of demands. On my psyche-centered version, we see that it is less burdensome to dispose of another's material holdings appropriately than to demand that they do so themselves. The latter involves both material sacrifice and ego-depletion. If you can instead find your way to my wallet without bothering my mind, then that's just fine. (Unless you're acting within a context where this would qualify as 'theft', of course.)