Brazil has an electronical urn for votations and it doesn't have a printed comprobation of your vote. This urn has been proven totally vulnerable for many years and now we - including the specialists who invaded the urn in tests - are talking about the printed vote.

My question is: a rigged urn wouldn't also give rigged prints? By example:

The ideal is: I vote X, the urn counts X and prints X.
The suggestion is: I vote X, the urn counts Y and prints Y.

But what would prevent the rigged urn from counting Y and printing X?