User blog comment:RemosPendragon/Chapter size/@comment-8395098-20150201151004/@comment-8395098-20150201200611

it's more they don't take SM in consideration for the thunderhawks, and then they act like there is maybe one at the most two SM per tank. now this is probably born more from bad retcons of previous codex events or failing to retcon some but based of the stupid numbers of tanks and armor flying at times due to writers, if you think about it realistically, from what it modernly takes to operate a tank, 3+ marines per tank, 2+ per rhino suddenly you have 450 marines down in some of theose battles to drive the tanks. they'd be down 400+ marines but then they are saying they've got 600 marines on the wall of the fort while they've got 300+ in drop pods all while the forementioned the tanks are out in the field doing whatever.

that said i think you have the math off a bit 40k no matter what is sitll more advanced than we are today, a cogitator (aka brain in a jar) can function far superiorly to a modern computer set so even wtih today needing 4 guys to operate i'm fairly sure that the SM could probably cut that down to maybe 2 marines. though the great lore fucker claims full WW2 style tank crews in Rogue Trader there are devices that should require 2+ inidivuals to operate but the device has a cogitator which makes it nearly automated enough that a untrained idiot can use it.