[RnMomof7]

And, as I'm sure you probably well know, the Church doesn't do annulments for the money. Any fee charged for an annulment is for the administrative costs of the process.

Why do they do them? By what authority??

As for cost..of course they make money..the people often have too hire "lawyers "( through the church of course) to make their argument or to fight the proceedings

[SumProVita]

“the people often have too (sic) hire “lawyers”

Hmmm, this is true....simply because you say so?

“Few Americans hate the Catholic Church, but millions hate what they THINK is the Catholic Church”. —Bishop Fulton Sheen

[Heliand]

Why do they do them? By what authority??

To ensure the flock of the faithful is in regular marriages and not committing adultery/bigamy/fornication, and because it is a Sacrament (Ephesians 5.32).

Authority - Matthew 16.16-18, 18.17-18, 1 Cor. 7.12-15, etc.