Any poetry competition that requires an entry fee is being run by those who are not serious about discovering talent or the expansion of aesthetic reality. I don't care how prestigious such an outfit is. Having to pay someone to judge the worth of your poem is absurd. And it's a kind of grubby lottery system, where the losers (not the outfit itself) will be paying for the grand prize.
I have a suspicion that many of these things are run by "important" and influential foundations. The entry fees might be, as I said, a way for the contest to pay for itself (which is grubby).
More likely, though, it boils down to this: "So you want US to read your -- *sniff* *sniff* -- poem? Well, you must pay dearly for the privilege of possibly wasting our 'important' and precious literary time."
A complete failure of humility and seriousness before the adventure of aesthetic discovery.