Overall there isn’t a reason to have voting machines, and if you do, they should really just print a piece of paper with your vote so that you can make sure it’s what you picked.
You’ll sometimes hear finance and efficiency as a reason, but unless American licensing for government software/hardware is significantly different from every where else, it’ll always be cheaper to manually count the votes than to buy voting software/hardware.
I mean, we digitised part of the process like I said, but we did it to make citizens wait less not because it was cheaper. It’s actually really expensive compared to doing manual voter registration, but we pay the money because no one likes queues.
Blockchain isn’t really a suitable option. It could be, but in the real world it would never be truly decentralised because no government is ever going to trust that, and if it isn’t, it’s just as easy to change and manipulate as any other database structure. And you still wouldn’t know if the voting machine actually did what you told it to do.
You can never vote from home in a democracy, because people might force you to vote a way you didn’t want to. I don’t really think groups would show up at your house to force you to do anything, but we frequently get husbands ask if they can vote for their wives, and if they could do that from home, no one would be there to stop them.
I know we live in a time where we want to digitise everything, but the paper vote is probably the safest and most efficient way to run voting in a democracy.