Let’s be clear that there never were any underage girls involved. Police placed ads pretending to be an adult female prostitute. Once contact was made the police officer pretended he was younger than 18. Most of those charged were not specifically looking for an underage prostitute. That’s why it’s called a “sting”. What confuses the issue is that the age of consent is 16 unless you’re a prostitute then you cannot consent until you’re 18.
Source: York police arrest 104 after officers pose as child sex workers | Toronto Star