I agree that each Cardinal certainly has free will. I do think that there is a great deal of safety in numbers in that (hopefully) nearly all of the 115 (or so) Cardinals will take their duty very, very seriously and do what they truely believe is best for the Church. Even if a few were to make a corrupt vote, it is not very likely that the person for which they voted would receive many/any other votes.
I recall a show (probably on EWTN) where they were explaining the promise that each Cardinal makes each time he brings his vote to the front of the Sistine Chapel.... Something like "I swear, as God as my witness, with the threat of eternal damnation, that the person for which I voted is the person which I truly believe should lead the Catholic Church". It was quite ominous. Perhaps I took liberties with the "eternal damnation" part, but I believe I'm close. I think that even an objectively bad Cardinal would think twice or three times before they cast their vote, for fear that they may be struck with a bolt of lightning (ZAPP! - or something like that) on judgement day. ..... Talk about a WHOPPER of a mortal sin. Yikes! Just try explaining to St. Peter at the pearly gates why you voted for someone other than the person whom is thought to be most-fit to take on the office of St. Peter.
Just my thoughts.