Being able to refund accidental purchases yourself is an awesome feature. But having only 3 per lifetime seems pretty low. Maybe you can tie this in with the tribunal as well. For example, you start out with 3 refunds that you graciously give us, then any additional refunds come from correctly punish/pardoning a certain amount of cases on the tribunal, like 100 or so. Heck, you can even do a special tribunal skin for having done so many cases. I don't do the tribunal too often so I'm not sure how many you can do a day. I think I could do 5 a day? So it would take me about a month if I accurately judged people?
Point being, while I don't see people using the refund feature too often, I think it would be nice to have the option of being able to earn refunds by being a positive member of the community and contributing time and effort to help make it better.