This has to do with the sales tax in Germany and when you have to pay it.
To put it in a nutshell: Generally, you would have to pay the sales tax (VAT) every month for every article you sent in, meaning you’d have to pay in advance since not all of your articles have been sold on Amazon yet. That is why we calculate the realistic price you are likely to make with your sales so that you only have to pay around the same amount of taxes in advance that you’d realistically have to pay later. This is better for your cash flow.