<<I can't agree with this if the developer is a non-profit organization that
survives on dues from it's members. >>
SEAONC does not survive on the dues from its members. Currently, seminars and (to a lesser extent publications) account for substantial revenue. Enough revenue to push us from the red into the black. If dues were to be the sole source of income, they would have to be increased to an unacceptable level.
Although seminar proceedings do not account for a substantial part of seminar revenue, if one gets the proceeding for a nominal fee there is no need to attend the seminar and you lose susbstantial revenue that way.
<<Sales can augment development costs, but the majority of work done on committees is volunteer.>>
NO, many of the more distinguished speakers work as consultants. Their presentations for SEAONC are free, but indirectly is advertising for their abilities. The slides they use contain their work product. A slide could take 10min to prepare on Powerpoint, but contains months or years of research or knowledge. That knowledge is what these consultants sell for a living.
<<Development cost also comes from grants and other sources of income to a
non-profit organization. >>
Some speakers do present information gathered under grants (such as SAC), however the majority are presenting their knowledge as indirect advertising of themselves or their firms, and are not paid.
<<I don't know enough about organizations like Plywood Association or AISC or AF&PA. Possibly those who are familiar with the workings of non-profit
material organizations such as these can enlighten us as to how much cost for
development is recouperated in the sale of documents.>>
You cannot compare material organizations to SEAOC. Their reason of being is selling millions if not billions of dollars of that material. They are easily supported by significant contributions from their corporate members. Sale of publications for them is a form of advertising. many will give those publications out for free. A $10 increase in fees for SEAOC would be a big issue, a $10,000 increase in corporate sponsorship is negligible.
Note: I come from an academic background and do support the sharing of information. However, SEAOC, though non-profit, does not operate in an academic atmosphere.