Each AAA region has its own 'rule' regarding distribution of the AAA Diamond Parking Pass. Generally, it's only given when you purchase a Walt Disney World Package from AAA, although some regions/offices give them along with ticket purchases, and it may be possible to find an office/region that hands them out to any member who asks.
There is a limited number of AAA Diamond spaces in each major park's lot, adjacent to the HP parking area and, as indicated above, NOT serviced by trams.
There ARE blackout periods - for example, I think all of December is blacked out at the Magic Kingdom. In addition to printed blackout dates, there may be other times when the passes are not honored due to expected crowds.
Most notably with the Magic Kingdom, anyway, you still need to walk from the designated parking spaces to the center aisle, then under a roadway, back up the other side, past where the trams drop off, to either the monorail or ferry. I'm NOT referring to anybody here, but... there are Guests who do everything within their power to reduce the distance between their Disney resort rooms and the bus stops/pools/dining to mere FEET because they don't want to walk "too far", who could then end up walking a quarter mile in the morning and the same distance in the evening to get from and to their car because they think it's more convenient
And what's even more interesting about what CarolA finds interesting is the people who BUY these passes on ebay.