Ping: your device, your router, your ISP's router, etc are already up and running and ready to participate in protocol interactions. Having done a bit of networ

Ping: your device, your router, your ISP's router, etc are already up and running and ready to participate in protocol interactions. Having done a bit of networking in the days where it was still reasonable to use analog modems as backup connectivity, I remember waiting 15-30 seconds for dial out + negotiation to occur before ping replies began flowing again. Car: your car is an integrated system where all the components have been selected with the intent of working together as an integrated system. A display device often supports many modes and has very few guarantees about how sources will behave, thus inter-device negotiation is needed upon connection. As other comments have noted, the control channel is fairly low bandwidth and there is potentially a decent sized chunk of info to exchange, plus timeouts and delays to ensure the display can work with older or less featured sources.