Their fees certainly aren't going towards liability insurance or fraud detection, so what are they doing with those fees?
I bet the fraud rate at KitSplit is going to go up after this post. Now you have a list of people that will wake up at 7am to hand over $4k of gear to you, knowing that KitSplit won't do anything and neither will law enforcement. Just remember to cancel your credit card and you'll make a quick $2k!
In all seriousness, if KitSplit wanted to stop this just charge renters a hefty deposit (the approximate cost of resell) and it should nip this in the bud. Obviously, someone in their "Growth" team will point out that this will hurt their KPIs and their VCs might not like it, so they won't do it.