Re: What about...
Well there is a big diffrence between a movie screening and a blessing or a curse.
First of you clearly know what you're buying. A moviegoing experience that will last a certain amount of time. The exact content of the film probably isn't known but that is a part of the agreement.
With a blessing/curse you're not buying the service of someone changting for X minutes and burning Y sticks of incense. You'd buy an actual curse or blessing. A negative or beneficial force acting against or in someone's interest.
Now with a movie you can clearly say in the end 'Yep, I saw a movie'. You can like it or dislike it but it's clear you got what you bought.
But after the chanting is done. How do you know this curse/blessing worked? ( Well you ought to know you threw away your money because magic is just bunk. )
There's no way to measure it, no way to say 'yep that bastard's cursed' and making it stick.