If a voter can cast their vote from their phone, anyone else can.
The strength of paper-based voting is in its cost and complexity: the number of confederates required to tamper with an election is prohibitively large. With app-based voting comes the risk of a large number of compromised phones tampering with elections.
The security downsides simply don't make sense next to mailed-in ballots, which capture the security (and accessibility) of paper ballots with the convenience of voting from home. The only upside of app-based voting is cost, which is a ridiculous factor to strongly optimize for when it comes to something as important as elections.
[1] https://en.wikipedia.org/wiki/United_States_presidential_ele...
Yes, it is. There are many ways such a system can go wrong. If its not this defective implementation, it'll be some other company's defective implementation. If not that, it'll be a targeted attack against the underlying platform.
Another big thing you have to think about is... Who will be choosing the system? Its going to be some bureaucrats with a vested interest in supporting one particular vendor, who use their power to silence any critics of said vendor's solution. Whenever electronic voting comes up, we always end up with this situation.
Biometrics are going to be almost impossible to do in a non-invasive and secure way for now, so cut that part of the pitch. Blockchain may not be an entirely round peg in this square hole, but there are other cryptographic architectures that probably make more sense (I am not a cryptographer, but maybe go talk to a competent one before just deciding on blockchain).
Obviously, without the two big buzzwords of blockchain and biometrics, you’re suddenly at a big disadvantage for VC money, but if mobile voting is ever going to be feasible, it’s going to need a considered, end-to-end approach that isn’t some MVP built from off-the-shelf components and off-the-shelf ideas.