I described the registration process in detail in many comments. I didn't describe it in every comment and then you jump on one comment and assume that it uses a database. It does not. It is incorrect to say it needs a database. It calculates a hash of information (name, physical address, etc) and looks that hash up in the blockchain to make sure the person is not already registered. Of course there can be fraud at that point by the registrar, the voter or both. The blockchain cannot stop that or solve that.
But there is no database. No database to be hacked surreptitiously anyway, just the blockchain holding the data and that cannot be hacked.
There is a database. It has to tie to valid voters, that valid voter list is in a database.