I have been through this exercise as I am on the board of a membership org with about 19,000 members (
www.uspsa.org) and a balloting standard that requires elections that use an independent, and auditable, process.
We use an independent CPA firm, providing them with database of eligible member names/addresses and the names for the ballots. They sent out serial numbered ballots, collect them, and report the results. In one case where they unintentionally used "Standard Mail" (marketing speak for what used to be called "bulk rate"), they had to do it twice - and match up ballot serial numbers to avoid duplicates (only the copy sent first class counted if both copies were returned). The organization did not have access to the serial numbers, who voted, etc. The cost for this annual election is in the thousands. We could run an election by mail ourselves for less, and do one on-line for even less - but that would undermine the integrity of the process and require that the members trust the persons counting the votes (who are under control of the elected leadership) - so that approach has not even been considered.
I spent some time speaking with Election Corporation of America which specializes in independent, secure balloting for private orgs using mail, internet and 800 number. Funny thing though - I sent the salesperson a breakdown of our costs and the balloting that concluded with "I am very interested if you can match our current cost structure. Any quote in excess of our current cost structure, even if it offers additional service, will be DOA. In any case, I would appreciate the courtesy of a reply". I never received ANY response, which tells me that this would have cost even more than the CPA route.
The current GOAL approach would never survive scrutiny for a corporate proxy vote or "real election", but also saves GOAL several thousand dollars a year over doing it in an auditable manner.
There are several issues:
1. Cost, cost and cost.
2. Tampering by voters (duplication of ballots, etc.)
3. Tampering by those in control of the vote counting
Reducing the possibility of #2 and #3 increases #1. As an org grows in size, cost becomes less important and maintaining the integrity of the election more so.