Presumably because it's hard to do correctly, and Stripe chose to focus on the easier part. For example, I need to report VAT on the 15th of the second followi

Presumably because it's hard to do correctly, and Stripe chose to focus on the easier part. For example, I need to report VAT on the 15th of the second following month. If I got a refund after that date, I have already reported that tax, and I need to report a correction. I can't just report a lower tax the next time. If you don't have a lot of refunds, then just paying taxes that you don't owe may be cheaper than handling it correctly (which is a lot of effort). And it may be the safer option -- nobody is going to fine you for paying too much tax.