Said no one ever. If anything, Singapore's government is considered one of the right wing governments in the world.
That's the problem with labeling something right wing or left wing, it doesn't tell the whole story. Singapore is a police state, everything is tightly controlled and you're under constant surveillance 24 hours a day. Some might call that "right wing", but if you use that as the criteria then you'd have to call oppressive governments like the old soviet union right wing, which traditionally were described as left wing.
Singapore is also very collectivist with healthcare, housing, and education paid for mostly by the state. That'd be thought of as left wing by most. Truth be told it's an authoritarian collectivist state, much more totalitarian in nature than free.