- mail-in is limited to municipality buildings
- mail-in is limited to wednesday-thursday in a week leading up to the election day
- you can go to any municipality regardless of your legal address
- you have to show your ID to get voting papers
- election officials and community supervisors are present in voting hall
- votes are counted along with normal votes after polling station closes on sunday
This doesn't scale that much because you can't verify the vote and you're limited to few days. It's pretty easy to spot it too. Other politics' support is on the lookout for returning cars and scout cheap bars too.
Now move this schema to postal voting. You've plenty of time to buy voting ballots off drunks. And you can fill them in yourself. It's much harder to spot too.
Yeah. It's so stupid that the Democrats don't knock the wind out of the Republicans' sails by embracing voter ID requirements coupled with an intense, funded push to provide an ID to everyone who lacks one (e.g. have government employees who go around to places like homeless shelters and jump through all the bureaucratic hoops and pay all the fees to get someone an ID).
Lacking official ID is a serious hindrance to modern life (and fixing that can have a lot of Catch 22s), so getting people ID is a great way to help the disadvantaged.
If my country allowed to vote without a national ID, I'd not trust the outcome of such election at all.