The fallacy of Tindie’s stated rationale for skimming shipping is that it discourages “gaming the system which creates a bad buying experience”. That’s utterly ridiculous - artificially inflating Tindie’s cut cannot possibly in any way discourage “gaming the system.” If anything, it may reduce the spikes but very likely only actually increases the “noise floor” of inflated shipping costs (i.e., not as many egregious offenders but who wouldn’t pad their shipping when they realize Tindie is skimming it anyway?). It’s still left to the individual buyer to complain if it seems the shipping cost is unreasonable. And then what happens? It’s dealt with on a case-by-case basis, as it should be anyway (without the skimming).
As I’m sure you’re aware, shipping cost is a horrible multi-dimensional problem in size, weight, distance, and a host of other factors. But the shippers’ API’s generally use size, weight, distance, and maybe starting point, so it shouldn’t be insurmountably infeasible to gauge reasonability of a shipping charge.
And that’s what it all comes down to - reasonability. Is some small, single-digit percentage of a item’s price a reasonable fee for what Tindie does? Absolutely, given the quality of the site’s support for the overall transaction process. Is counting shipping AND the payment processing charge as part of the item’s price reasonable given that Tindie does nothing for shipping and shovels the same bits around whether the transaction is $5 or $5000? (And don’t believe for an instant that Tindie isn’t already making money on the “%+fixed” payment processing fee.) So Tindie is double-dipping by including shipping and payment processing in their fee calculation. Is this in any way reasonable? Sorry, no way.
So the next “justification” becomes “thousands of orders” and your “…is standard across the whole field”. So? How laughably irrelevant are both of those? The real answer is “because we can”. The next red herring someone will roll out is “…but it’s a trivial amount of money in the end”. Again, so? That’s not the point. The point is reasonability.
A double-dipping skimming scam fails the reasonability test. Period.
(And yes, there are other shop sites that don’t appear to be running this same Tindie-style skim/scam. At least, it hasn’t yet become obvious. Tindie’s big hook is its more “techie” clientele, so it gets the volume and the attention in this space and everything’s just wonderful, right? Until you peel the onion and apply even a little reasonability.)