Because it isn't permissible? This seems like a loaded question. I've never actually been served this sort of avoda zara (apparently it's not as widespread as its worshippers like to insinuate) but if I was I'd be sure not to eat it.

Or...the custom didn't come from that?

@Harel13 Even if you're correct, it's not clear to me that a practice which independently evolved, but which bears striking resemblance to an idolatrous practice, is permissible. For example, playing music in shul during davening (let's assume not on Shabbos itself, or else on Shabbos by a non-Jew so as to be a שבות דשבות לצורך ציבור) was still forbidden by orthodox Enlightenment-era Rabbis on the grounds that it was חוקת הגוים.

@AA I would be inclined to agree with you. I guess I'm asking, how do those who do practice this service defend the practice?

I thought that playing music in Shul was forbidden because that was limited to the Beis Hamikdash, or to the time when there is a Beis Hamikdash - similar to other limitations on music (which vary quite a bit depending on who you ask...)

@manasseh I have not heard of such a psak but would not be surprised if someone suggests that. Playing music in general may be prohibited for the reasons you cite (source being בשיר לא ישתו יין), but generally people who have even heard of the halacha seem to follow the leniency of the Rema (originally Rashi) that it is only forbidden while eating, with the exceptions of weddings, Shabbos, and other "musics of mitzvos."

Apart from the chukas hagoy question, why should it be allowed to bake a key into bread to improve the chances of good parnossoh - it contradicts our faith in Who controls parnossoh.

When I was a kid we used to do it but then my parents found out its source and haven’t done it since.