How are you paying Bitrefill?
There really isn't a lot to unpack.
To me, the cost of Netflix is peanuts. Its not worth worrying about.
I don't have to do anything at all in regards my paying for it, its by default added to my phone bill.
No need for gift cards or any such nonsense.
If the cost of Netflix became an issue to me, I may consider looking for alternate means, but its not, its basically not even of any significance to me and hence I CBA with any messing about.
Easy, hard, medium, irrelevant.