I think if a social media organization encouraged a #highspeedometer hashtag they could also be liable. It's not the filter or the speedometer, it's that Snapchat set up a defacto social incentive for speeding.
IMO this is an inconsistent approach of placing responsability. What about regular people who start viral challenges that might get people killed? Should they also be held responsible? If the answer is no (in the real world, the answer is no), then why should Snapchat should be held accountable?
I cannot help the feel that this "social incentive" argument is the adult cousin of "but everyone's doing it, mom!".
I'm not so sure the real world answer is "no". What are you basing it on? Why are organisations that promote dangerous activities (e.g. paragliding, cycling challenges) asking me to sign liability waivers? I think this is evidence against your claim in the real world.
I believe the comparison to "viral challenges" is in relation to the "Tide Pod Challenge" as it was started by people of the general public - not an organization.
I'm saying organisations are making me sign liability waivers when they knowingly promote something dangerous. I wouldn't be surprised if someone sued an individual who promoted dangerous stuff and did not absolve self from liability, be it via virtual challenge or other means.
I think that is the case that the product itself of providing a speed filter would not be an issue unless marketed in a way to encourage non safety. For the product to be considered unsafe they would have to do something drastic like not enable the filter until exceeding posted speed limits or something.
Even marketing would be tough to catch them on as how many grocery stores in college towns sell beer bongs right next to beer displays that are a few feet away from liquor. At what point would they be liable? Beer bong directly adjacent to bottles of JD/ shrink-wrapped with bottle/ buy 2 bottles of JD get a beer bong.
I cannot help the feel that this "social incentive" argument is the adult cousin of "but everyone's doing it, mom!".