Events tend to go on the fixtures list a long time before any of the event arrangements are made: in my experience they usually don't have a planner, controller or organiser, or any precise details about where the start, finish, parking etc are, let alone what the course lengths are or what the entry fees will be, or the start times and closing time.
Usually, once these details are pinned down, the event goes live for entries.
For League events, say, we know the courses (except for the question of whether there will be a Short Green or not) but we don't know the course lengths, which in some cases determine which course someone will do, particularly if people are undecided between Brown, Blue and Green, say. (This won't affect the serious League competitors as much as the more casual or occasional ones).
These are the reasons I see why entries don't go live earlier, not an answer to the question why these can't be pinned down more in advance.
The related question is when to close online entries and what to do about entry on the day. Printing extra maps is no problem and is not as wasteful as having hundred of obsolete maps stored somewhere - as in the pre-OCAD/digital printing age where you had to print several thousand maps to make the print run viable.
Online entries are a benefit mainly to the event organisers (to populate the results software and to estimate the final numbers at the event), unless the entry fee is cheaper than the entry on the day rate, when the competitors also benefit. Currently, entering in advance doesn't guarantee you a map if the number of EOD's is high and/or the organisers underestimated the number of maps to print. An extra map, on waterproof paper, will cost about 70 c to €1, which is well covered by the entry fees, particularly if the EOD fee is higher.
You will have seen that NIOA events charge a significantly higher entry fee than we do (and don't usually provide the tea and biscuits etc that we do) so I think we are undercharging. We also should have a reduced rate for club members (all clubs, not just the organisers) than for non-members, to encourage people to join clubs.
In 3ROC's case we usually close entry for a Sunday event at about midnight on the Thursday, and print the maps on Friday with some extras for EOD. I don't think there are any printers open on Saturday (Reads used to be, but not any more, I think).
We need to have enough maps to guarantee that everyone gets a new one and certainly that all the pre-entered people are sure to get one.
John McC