Because a robust PKI-verified vote is a prerequisite for verifiable vote buying. The problem case is almost completely unlike e.g. online banking, which anyone "well-versed in PKI technology" should realize by themselves.

Hear hear.

Any security engineer / technical security auditor worth his salt will a) point that out to you in a meeting b) prove it to you through pentesting if needed.

SCADA systems in general are on the more .. interesting side from a security testing point of view, as one has to be _pretty_ careful about any side-effects caused by the testing. Been there, done that, haven't (yet) caused any major disasters.. ;)

As so many digital-age inventions, this has been done in Finland ages ago. :) There's even a company whose business is built around it: http://www.upc.fi/en/upcode/