Because petitionary prayer isn’t the only form of prayer we are to practice. There are many forms of prayer: meditation, contemplation, petition, praise, thanksgiving, etc.
(Snip)
To Starcrash:
The above is a very important point and one that should not be overlooked when considering the whole matter of prayer. Meditative, contemplative prayer, prayer of abject praise and thanksgiving should be by far the greatest par of our prayer life whether formal or informal.
It is in this way that we grow closer to God and gain a greater understanding of His will for us and for the world.
These forms of prayer are like “visiting a friend”, someone you are close to and who you can tell everything about your life.
In such a relationship one does not constantly go to such a friend - even someone close - and constantly ask for favors…
Instead, you visit with them. you listen to them, you grow closer to them, you learn their likes and dislikes, you try to please them and you accept their friendship in return. Not for what they can give you or what favor’s you might be able to get from them but simply because they are your friend.
In such a relationship - if and when you DO ask a favor, this friend is more likely to grant it or - if they can’t for some reason they will try to explain to you why they can’t grant what you ask.
And you - being the good friend that YOU are, accept whatever the response is…Because you know and trust your friend…
But - I ask you then - How would you measure scientifically the efficacy of the friendship(s) and the quantity and quality of the responses to various requests/conversations? how does one scientifically measure “friendship” or a “Love” relationship?

Peace
James