I think the 7000 member thing is a red herring. Whilst there are 7000 members, how many of them are actually active on a given month? Sure some of you will do a ride on every weekend in the summer (and winter too), but the reality is that most members aren't. It's probably safe to apply the 80/20 rule here. 80% of the brevet cards are done by 20% of the people.
Part of this then becomes expectation management. How long do people expect it to take to get their cards back? Who's in a hurry?
Oh, and as for posting stuff, if you have a good relationship with your local postoffice, shipping 10 items, and shipping 200 isn't that much different in effort.
Based on the numbers here for 2016:
http://www.aukweb.net/_resources/files/AGM_Papers.pdfThere are somewhere around 540 events per year (c.f. Breakdown of events by distance and year). Some organisers have multiple events on a single day so we'll say there needs to be ~450 separate batches of Brevet Cards mailed out to the organisers.
Then, assuming no electronic validation, those 450 batches of cards will be sent in for validation. Once validated those 450 batches of cards will be returned to the organisers for distribution back to riders.
Almost 2 parcels per weekday for the entire year, you're going to get to know your local postie very well and the local post office staff.
BRM events are roughly ~50 in non-PBP years and ~100 in PBP years. That adds to the admin overhead of the Recorder/Validation process (not sure if anything ever needs to be posted for these any more).
As for calendar event rider numbers (c.f. Breakdown by distance):
50 km 1118
100 km 10805
150 km 1190
200 km 6200
300 km 1006
400 km 647
600 km 456
1000 km 38
1200 km 27
for a total of 21487 Brevet Cards.
There were also a total of 5067 DIY/Perms (Perms 1764, DIY 3108, ECE 195) but most of the DIY and ECE rides will be 'virtual' brevet cards.