Can bitcoin technology be used to end election fraud globally?
No, absolutely not. In any form of voting, and individual cannot have ANY means of proving which way they voted. Why? Because allowing voters to prove how they voted
opens the market to vote-selling.
Voting must be done in such a way that: I, as an individual, cannot prove to any other party how I voted. It doesn't matter if the system is pseudo-anonymous like Bitcoin -- I can still show someone my private keys / sign a message / whatever.
There is also no way, mathematically, to 1) verify that each individual is authorized to vote and votes only once, while 2) not allowing that individual to prove which way they voted. You need to trust a third party for that.