because in an ecash system, the user creates the ecash, and the mint blinly signs it.

It's a user-mint interaction, that only works if both parties play by the book.

It's not just like the provider/bank says they are using ecash, and you have to trust them. 

If you don't understand or would like to know more on how it works, let me know 

 Thanks, that helps. If you have a link that explains it more I wouldn't mind taking a look 

 https://fedimint.org/docs/intro

I really liked the video explaining it on the fedimint page 😊