I suspect, but cannot confirm or even really look up, that they cheaped out on some of the switch infrastructure in the middle. Also, at least some of the radars I dealt with produced object data and that meant that they had a defined "frame" size of 65536, even though it would often be mostly zeros, so it had to do fragmentation no matter how you set up jumbo frames and that needed to be handled at the sensor firmware level. There's also some tradeoffs inherent in gigabit speed T1 automotive ethernet and some stuff that was defined at the mac layer rather than the packet layer. Happy to chat more about it, feel free to look up my email in my profile.