Etsy generally doesn’t go into selling services IIRC, and a lot people selling this stuff on Etsy sell “I will do a spell/psychic healing/remote reiki/whatever”, which is a service.
Also, even in the case of having the parts of a spell shipped to you, how do you do a payment dispute when the spell doesn’t work?
And where would you even go to buy spells in real life
There's places in pretty much every major city, and even in some surprisingly rural places. Even in ritzy neighborhoods, there are private and public palm readers and tarot card shops catering to the upper crust who will sell anything they can get away with.
In places like New Orleans there's an entire tourism sector for it.
Also, even in the case of having the parts of a spell shipped to you, how do you do a payment dispute when the spell doesn’t work?