Does all of Israel sell its chametz through the chief rabbinate? If so, why?
It's been reported that the same non-Jew buys all of Israel's chametz before Pesach. Indeed, I've heard that all rabbis in the country who are authorized to sell chametz transfer that authority to their respective municipal/regional chief rabbis, who transfer it to the national chief rabbis, who effect the sale.
I find this hard to believe — or, at least, it's hard for me to imagine why it should be the case. Between the plethora of valid halachic opinions regarding how to properly sell chametz, which may lead some stricter people to deem the chief rabbinate's sale insufficient, and (l'havdil) the politics that sometimes unfortunately accompany religion, which may lead some to deem the chief rabbinate's sale inappropriate, I'm astonished that everyone sells chametz through the chief rabbinate. Is it really true? Can someone cite a more believable source than a newspaper article that writes in general terms? If it is true, then why is this the one religious matter that everyone has managed to agree on?