I suspect it is just idiomatic ('to be had' = available), but it does occur with other verbs: There's a lot to be learned about those people. There's much to be admired in the way they have recovered. etc.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
tashiroI have never seen "have" used as a passive verb.Well, there's a first time for everything!