To the contrary, it has been dealt with ad nauseam, usually erroneously. This statement is patently false. While an identity-based system would be one way to accomplish these objectives, a voucher system would serve just as well. The problem of disassociating the vote from its origin, i.e. location of the phone, is much more resistant to solution. All voting systems are subject to abuse, not the least are those systems currently in use.
All voting systems have some problems of equity.
In many of our current systems, these problems were deliberately engineered in for political motives. These problems resist solution precisely because any change will shift the political balance, however slightly. To the extent that we can move to systems that are more secure, more equitable, and more economic, we should do so. Such systems clearly exist. My personal preference is for more equity.