Morty Vicar
Banned
The essential difference for your Scottish example, is that some eligible voters, choose of their own free will not to participate. That's on them, and they get to live with the impact of their inaction. A wise woman once told me that she was going to vote, even though she though both candidates were "worthless a$$holes". She voted anyway, as she felt that gave her the functional right to complain about the outcome. If she did not choose to vote, she felt that she forfeitted any claim on complaint.
I kind of agree with that. Even spoiling your ballot paper makes some sort of a statement at least, although it's also pointless. Russell Brand made a big deal about the BNP in some documentary, but then a few years later he announces he doesn't vote because 'it's a waste of time'. So if the BNP do get in imo he has no right to protest.