There might be some reason for this (again I am not a pro, but just spit balling)- rollover rates on crash of EV is much lower, so I am suspecting they don’t care as much to ensure roof integrity. A strong roof is probably a legacy of gas autos, so anyone who is starting fresh is probably much more likely to question it than those trying to have a ev car lineup similar to their gas car lineup.

Also for the same area, is glass heavier than steel / aluminum?