I assumed it's because the crown corp running the park system was a huge cost to the government, which would come under fire in other provinces. But from Sépaq's 2025 financial statment (PDF, in french) their income was $261.8 million and their expenses were $261.3 million giving them a profit of $459,000 which they say they reinvest into parks. Even small government advocates would have a hard time arguing this crown corp should be privatized.