That's how it is done in Belgium.
Think of it. If your choice is ether vote or risk a fine, you'd rather go and vote. If you go and vote, you'll learn at least a bit about the choices you have to make in the ballot.
P.S. While Belgium got mandatory voting right, it completely messed up electronic voting. I remember being an assessor in a polling station with electronic voting.
People voted, then the head of the voting station took 3 1⁄2-inch floppy disks out of the machine, put them in an envelope and drove away to the district polling committee. There was not counting, no protocol to sign. Nothing. I was appalled.
This is ABSOLUTELY not what I want. I for one want voting to be extremely accessible. Everyone that wants to vote can. The goal isn't to make everyone vote but rather that everyone has the ability to vote. That you don't have to take time off to vote. That it is easy.
Universally accessible, not universally mandated.
On the other hand, casting a vote doesn't mean CHOOSING a candidate. It means that you can cast a BLANK vote. And that, in and of itself is an extremely important thing. It shows that you are NOT okay with either candidates, and forces them to actually adjust their agendas to suit the "public will", instead of falling back to what I believe is commonly called in the US as "ratfucking", aggressive districting, and voter disenfranchisement, which means they literally only care about getting enough voters to pass.
As for the doability, it's already done in Australia. Pretty successful, and basically and national holiday celebrated like 4th of july in the US.
That's the pesky thing about democracy, you see. If you want "informed voters" then you actually have to work to have an informed populace, not gripe about people's right to participate in the society they're a part of.
Not everybody has to be your idea of an intellectual to be a part of a democracy. And not only is that okay, it's precisely the point of it being a "democracy".
Yes, and the solution to this is not mandating that they vote. If they are uninformed forcing them to vote doesn't cause them to be informed. It makes the system more vulnerable to populism.
The idea behind freedom is not absolute freedom. It is a balance of the contract with society vs individual freedom. You want to maximize individual freedom, but for everyone (not a singular person). Clearly things like the "freedom" to murder someone doesn't outweigh that person's individual freedom to live and thus we make laws (and ways to enforce them). Mandating voting decreases individual freedom and has a potential for reduced societal freedom (while little to no real potential for increase. Much prone to populist candidates). So why mandate? Don't solve problems that aren't problems. If someone doesn't want to vote, how does that harm you?
In general, people don't trust elections because they don't trust their representatives to actually represent their interests, or they don't trust the rest of the political system to actually allow any meaningful change. These are very valid and correct criticisms, confirmed by many sociological studies (in the US at least, the opinions of the bottom 50% of the electorate by wealth have almost no influence on their representatives' agendas).
Voter suppression and vote buying/bullying are much more common, but those have little to do with the voting system (though India has an interesting and complex voting system designed to combat a history of systematic retaliation against entire groups of voters, such as de-funding entire regions that had voted the with the losing party).
But actual voter fraud is rare in most democracies. It's extremely common in authoritarian regimes that are mascarading as democracies, but an online system would make those cases especially trivial.
For example every election in Washington ballots are mailed out to every address on file, it’s very easy to print a ballot online if you didn’t get it in the mail, and until recently there have been no supposed issues with mailing ballots (postage is prepaid), plus there are dedicated dropoff boxes as well. And even with all that convenience turnout was 65% in 2016, though it is expected to be higher this year.
Reliable on-line secret ballots do not exist for us yet and may never.
More easy-to-access polling stations does.
The internal handling of votes should be harden as you explain, but helping more people to vote should be the goal. The reverse is also an attack on democracy, and we already see this at so many scales.
Like setting voting stations at places easier to access for a specific portion of the population (right next to churches on sundays, next to police stations, hard to reach by public transport places, etc.). Reliable online voting would alleviate these kind of issues.
Not saying it’s easy, but we should at least try.