Just as planes evolved over the course of the war, so did AAA. The early war AAA had a difficult time reaching high enough to do damage, didn't have proximity fusing, was visually directed, and yes, mostly hand-cranked. You see things like 37mm and 20mm manually directed guns, 4" guns with hand-cut fusing, etc.
Contrast that with the late war ack - radar directed large caliber guns with proximity fusing shooting down inbound V-1s for example. Quad 40mms (and not hand cranked anymore), along with 5" radar directed fire from ships. For sure, the old 88mm didn't have much trouble reaching up high to touch you.
We don't have the ack towers at fields, or the old Ma-Deuce (which was manually directed, but could still ruin your day pretty effectively if you came in at low alt). The current ack system while not perfect is a fairly reasonable compromise, although the puffy ack system could use work (frankly, I never see it shoot down much of anything - its worthless as it is).
And as far as hitting a crossing 400mph target coming low alt over a field goes - you aren't a crossing target to every gun (or gunner), and I've shot down plenty of guys as they go whistling right over a gun and drive right through the stream of lead.
