Except Snapchat doesn’t have to surveil its customers and we really don’t want it to.
Does Apple surveil iMessages? Does your cell carrier need to monitor your text messages? Does it listen to your calls to see if you make terroristic threats?
Some bad things might be prevented if we “listened in” to all communications and then triggered a police response when something alarming was said. But doing so is ripe for abuse by those in power as well and that’s why warrants are required before surveillance and the invasion of your privacy is allowed. No warrant was necessary here because Snapchat makes you accept the surveillance under its terms of use, which all apps and cell carriers could technically do. And your Amazon Alexas. We don’t want that. Without privacy you don’t have freedom.