It's legal to be a prostitute in all European countries.
However in five of them it's illegal to be a customer. This was put in place partly because it's a bit of a grey area whether the prostitute is always willing or possibly forced to do it, but a customer is always willingly visiting a prostitute.
In most European countries it's perfectly legal to be both a prostitute and a customer though, but illegal to own a brothel or be a pimp. If the prostitute has to hand any of their money over to anyone else besides the government in the form of taxes, that other person is in big trouble. Here prostitutes are considered self-employed entrepreneurs.
And then there's a few countries where brothels are legal, but regulated.
No reason why specifically Canada is the customer here. I just needed a harmless dude from a country where prostitution is illegal.