Why don't kids ride the school bus anymore in California?

Maybe it's just me but growing up outside of the Sacramento area, there were usually always a ton of buses driving kids to school. Everyday I would drive by the local elementary school, there would usually always be a school bus there by around 7:50AM and all the kids would hop on and ride it to school. Nowadays, I drive by the school and the school buses stopped coming for some reason? Usually I would see medium sized buses driving special ed kids to school, but regular kids not riding the bus anymore in my area seems kinda weird to me.