I take your point but there is a lot of "silent recruiting" that goes on where jobs are never advertised in the aviation press or on company websites. Companies say "why pay several hundred pounds to put an add in Flight International when we get sent 500 CV's each week?".
Yes you can do you research and target certain companies who you know are recruiting and those you are likely to gain employment with (ie I don't send CV's to Virgin but I do to flybe), but to be in with the best chance you have to have a little bit of the "be in it to win it" approach. The worst thing that can happen when you send a CV to somebody is that they put it in the bin. 26 pence for a first class stamp is not that much of an investment when you're looking for that first job.
Most of the people I know who fly in the airlines did not receive any form of reply from sending their CV until said company phoned up asking "can you come for an interview next week" - one case many months after the CV was sent.