That's actually a good question. I understand how including the most txes with the most fees per kVB will mean including the maximum number of txes with the largest fees. But I can't help think about flat fee.
Let's assume someone broadcasts a tx with a ton of inputs and a chunky script size. If it only uses 1/3rd the average of network fees/byte, (
https://bitcoinfees.earn.com/ I generally use this website to see the minimum fee needed for the tx to be confirmed in the next block), but even with very low fees, the flat payout for this big transaction is considerable, is it still going to be seen as any other tx? So by pure satoshis/byte? I always wondered if miners choose to ignore these kind of transactions.