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if you wanted to commit voting fraud, you'd probably exploit postal voting
That's usually how it's done, for efficiency rather than simply because it's less secure than voting in person. One householder can complete dozens of postal votes for real or imaginary members of his household, while personation at the polling station can be done only once or twice before detection becomes all but certain.
Also, my opinion is that if you wanted to commit voting fraud, you'd probably exploit postal voting, which no longer requires any particular justification, and would bypass any in-person ID checks.