The dumb thing is that these voting systems are even able to be reached via the internet.  If you want a secure system, it's easy.  Each center runs a complete system of voting systems and servers which are air gapped from anything else.  The voting systems store results on the redundant servers locally, with no connection to anything else.  Results are transferred to secure media which can be used to update a centralized system with results periodically.  Impossible to hack without physical access to the systems.