ShotOne,
That would only be a fair comparison if airport employees' social clubs and guest accommodation were airside, which they aren't, and if a significant number of airport workers lived airside, which they don't.
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A great advantage of the US system of maintaining the link between the retired community and the base is that the potential market for on-base shops, social facilities, etc is greatly increased - all of which benefits the serving inhabitants through e.g. having a large and cheap supermarket on site. Then there are the intangible benefits to the moral component of fighting power accrued from unforced and natural social contact between the retired generation and the serving 'youth'.
The US can manage this without a problem because they have a much more layered approach to security than does the typical British military base, and hence can be less worried about the number of 'social' passes issued to families and veterans. British bases are slowly changing as infrastructure gets rebuilt, with the introduction of proximity cards, touchpads or other forms of control of access for the more sensitive areas. I wonder if this might, in time, result in a slightly more 'can-do' attitude to social visitors to domestic areas?
Finally - security clearances 'lapsing'. AIUI retirees are required to hand back their passes almost immediately, thereby losing their rights of access, but their security-cleared status (i.e. SC, DV, etc) continues until its next renewal date (note, being 'security-cleared' does not actually get you anywhere unless you have relevant employment). Cleared status has traditionally been seen as an attractive CV item when applying to certain sectors of industry as it saves them paying for it themselves. Finding the vaguest of reasons to get clearances renewed towards the end of a final tour of duty has been a long-standing wheeze!