That is a good question, and what I'm about to say is not a full answer. But I do give some of credence to this tweet because it is the original claimant publicly admitting they are wrong, which is a costly act that puts skin in the game. Now if it is found that it is true that Apple does keep the %30, the claimant is going to take an even harder hit.
There is also the matter of prior probabilities; if you had asked me beforehand "How certain are you that if Apple refunds a charge, the refund is complete and they also refund their cut?" I'd have given you an answer in the 90%+ range, on the grounds that if they did something that nasty we'd have heard by now. Furthermore, if they did change that policy, I'd expect to hear about it precisely as a change in policy, rather than the sudden discovery that it's been like that all the time.
I am emphatically not holding these up as total answers to the question. I'm not sure there is such a thing. But these are reasons to consider this tweet likelier to be true than the original claim.
There is also the constant possibility "What if somebody knows about these signals and fakes them?" In which case the question is, who would have motivation to do such a thing? In this case I can't see how this Tweeter has any particular motivation to fake this matter, as this retraction mostly doesn't benefit them any. (I mean, I do respect them for it, but we still have the original error to consider. I don't have a concrete threshold, but you're still burning a bit of rep. To see it clearly, consider the strategy of "impress jerf by making lots of public mistakes and then publicly apologize for it"... I do respect the public retraction and maybe the first time it's even a net gain, but it's not a scalable strategy.)
Apple would clearly have a motivation to claim they don't keep the refund even if they in fact do, as clearly keeping that 30% would be bad PR, so this signal would weigh against them. Weighing for them, though, would be the sheer mass of people who could contradict them if they claimed not to keep it but in fact did; any app author of any significant size has direct experience with this and that's a large pool of people, which also includes some vocal people in it.
There is also the matter of prior probabilities; if you had asked me beforehand "How certain are you that if Apple refunds a charge, the refund is complete and they also refund their cut?" I'd have given you an answer in the 90%+ range, on the grounds that if they did something that nasty we'd have heard by now. Furthermore, if they did change that policy, I'd expect to hear about it precisely as a change in policy, rather than the sudden discovery that it's been like that all the time.
I am emphatically not holding these up as total answers to the question. I'm not sure there is such a thing. But these are reasons to consider this tweet likelier to be true than the original claim.
There is also the constant possibility "What if somebody knows about these signals and fakes them?" In which case the question is, who would have motivation to do such a thing? In this case I can't see how this Tweeter has any particular motivation to fake this matter, as this retraction mostly doesn't benefit them any. (I mean, I do respect them for it, but we still have the original error to consider. I don't have a concrete threshold, but you're still burning a bit of rep. To see it clearly, consider the strategy of "impress jerf by making lots of public mistakes and then publicly apologize for it"... I do respect the public retraction and maybe the first time it's even a net gain, but it's not a scalable strategy.)
Apple would clearly have a motivation to claim they don't keep the refund even if they in fact do, as clearly keeping that 30% would be bad PR, so this signal would weigh against them. Weighing for them, though, would be the sheer mass of people who could contradict them if they claimed not to keep it but in fact did; any app author of any significant size has direct experience with this and that's a large pool of people, which also includes some vocal people in it.