All things being equal (eg corruption level, education, etc) I'd assume people consider the second more legitimate. They are happy with how their government would turn out, and even though they could potentially have 10 times the voting impact, they choose not to exercise their right.

That's one possible reason why they might refrain from voting. They might also be unhappy with how their government would turn out whether they vote or not. In my experience, people who don't care about voting are much more likely to be disaffected ("they're all idiots so it doesn't matter,") than they are to be satisfied ("they're all good enough as far as I'm concerned." )

I think that people who're enfranchised and largely satisfied with government are much more likely to participate in its operation than people who're enfranchised but unhappy. If most of the public agrees on the major subjects of debate between parties, the party lines will shift until they don't, and the people who're not too disenchanted with the whole system to participate will continue to have candidates the differences between whom they care about.