This is going to come as a real shocker to my non-Singaporean friends who read this blog.
In Singapore, voting is not a right guaranteed under the Singapore Constitution.
You can say what you want about Thio Li Ann (controversial is putting it lightly), but this question has long been in the asking. As a constitutional law "expert", it's only natural to expect her to ask this question at some point.
Based on our Constitution, the PAP's 82 out of 84 seat majority, and the solidarity of the PAP (which has an effective whip), it's not really an exaggeration to say that our current government can essentially alter the highest law of the land at will.
Yet it remains a curious anachronism that despite the years since independence and the supermajorities that the current ruling party has held in the intervening time, our government has not seen the need, nay, the moral imperative (seeing as how we are a democracy), to enshrine the right to vote in the Constitution, as opposed to leaving the right to vote in its rather ambiguous position today.
But then again, why bother? After all, the current party's supermajority, and by extension, ability to alter the Constitution, will persist for the foreseeable future almost indefinitely. Easy come, easy go...