My question is, is it legal for some officers in Ontario to use their lights other than for emergency calls?

The short answer is YES. Police officers in Ontario can use their emergency equipment for any lawful policing purpose, and that's intentionally pretty broad. One of the things people frequently complain about is seeing a police car approach a red light, turn on its lights and siren, proceed through the intersection, and then immediately turn them off. The assumption is often, "They just turned them on so they could run the red light." Well, yes, they did, because that's what the law requires them to do. In Ontario, when a police officer needs to proceed through a red traffic signal, they must come to a complete stop, have their required lights and siren activated, make sure it is safe, and only then proceed through the red signal. So why turn the lights and siren off afterward? Because there's no requirement to leave them on just because they're responding to a call, and there are plenty of reasons why an officer may not want to. At night, running a siren unnecessarily can wake an entire neighbourhood. Lights and sirens can also create additional distraction and risk for other road users. In some circumstances, officers don't want to advertise their approach to the very people they're trying to catch. And here's one that surprises people: sometimes lights and sirens actually slow police down. Drivers can become extremely unpredictable around emergency vehicles. Some stop in the middle of the road. Some slam on their brakes. Some move in the wrong direction. Others simply panic because they don't know what to do. There are situations where an officer can get somewhere faster and more safely without using emergency equipment continuously. So when you see a police officer activate their lights and siren to come to a complete stop and safely proceed through a red light, then turn them off afterward, that isn't necessarily an abuse of authority or someone using their emergency equipment to "beat the light." They may simply be doing exactly what the Highway Traffic Act requires them to do.