Unless you are a dive proffessional, you do not belong to any agency, you just buy training from them.
And as a point of intrest, when did NAUI stop being a nonprofit?
Bob
Again, not strictly true.
It very much depends on the ethos of the organisation.
PADI (among others) are a commercial organisation, with an objective to make a profit, for the owners/share holders. The instructors are agents of the organisation.
The BSAC, is a members club, it is run for the benefit of its members. They 'may' be instructors, they 'may' be officers of the individual branches, they 'may' be members of the BSAC council.
The vast majority of members are just divers, who pay their annual membership fee. Some members are direct members, who pay just the BSAC membership and are a member of BSAC, having access to services and training run by HQ or the regions. Most are branch members, paying both the BSAC membership, and a branch membership. No two branches are the same, the facilities provided by the branches differ significantly. Some have limited additional features, other than a group who want to go diving. Most provide diver training. Some have additional, facilities, compressors, blending stations, RHIB's, some even own large boats.
There are also 'special branches', all military recreational diving is done via 'special branches'. Universities have special branches, as do some companies.
Although a member of SISAC in the East of the UK, I have dived with Penzance Branch in the South Westpast. Having phoned their diving officer and asked if I could join them whilst I was in the area. The cost to me was a contribution to the fuel, and a few pints in the bar.
It is perhaps a peculiar feature of the British. We form clubs, Football (Soccer), Rugby, Cricket, Bowls, Dining, Drinking, Polo etc. Some are complete informal, others have a structure and an affiliation to a governing body.