All the major manufacturers use proprietary Remote start systems for their cars. Just like they use their own infotainment systems, engines, and so on. Now that isn't to say that Jeep/FCA specifically make the remote start system that is installed, but it isn't a third party part if they do, it would be more like second party. They use vendors like Continental Teves, TRW, and ones like that to develop solutions specifically for them. So you are right there are parts and technology that doesn't make sense on them developing in house, but they go to Vendors who do specialize in that to make a system proprietary to their cars, so even if TRW was doing work for Ford and GM, the two systems aren't compatible. These suppliers tend to only work for the OEM's and don't have retail solutions out there.