Now let's see despite these advantages why SEO doesn't work.
Firstly there is no coordination between the client and the provider. The terms and policies should be explained in a detailed way to the client but in many cases the provider try to hide some minute points which are important and should be known by the client. Even though it is trivial every condition should be frankly explicated so that no future query of any kind arises. But as this process is seldom carried out SEO often fail in their fundamental aim.
Then the second reason is that a client sometimes selects an unfit provider just because he was good-mannered or he spoke well or sometimes due to the only reason that he is a low-budget provider. When selecting a provider the thing which should be kept in mind firmly is that the provider should be a professional with a very good experience in this field. Even if he demands a little more money the work will be perfect and one more thing is he should be given time to develop the SEO and for SEO to flourish and provide benefits. Haste will bring only misery.
Another wrong assumption by the clients is that if their ad gets placed in the cover page they will get maximum benefits. But it is not the case usually. For an ad to come in the main or cover page it will take time and will destroy your chance to grow fast. But an ad placed in a number of papers will do well and will get you much more benefits as people expect variety and the will to grow fast rather than popularity.
Some other simple reasons which make SEO a bane rather than boon are
* Failure to be in contact with your provider constantly will block you from the events which happen in the site and will isolate you from the site. Later when you visit the site and complain about the lack in progress the provider will put the blame on you for being careless even if there was a mistake on him. So your site should be visited regularly and a constant communication should exist with the provider for a better deal and for the business to grow as you had expected.
* Moreover the site should be updated frequently of the current affairs and changes happening in the organization which will improve the traffic and thus get business to expand. But failing to do this will cause the business to be stagnant and sometimes even drop down.
These are some foolproof reasons for why SEO don't work the way you expect them to be and why they fail you inexplicably.