It really. Anyone with money has good coverage plus umbrella.

I looked into it as I prefer to self-insure for any non-catastrophic risk.

It makes absolutely no sense for me to post a bond for such a small amount when I can get ~10x the coverage, plus all the claims handling, for $1200/yr for two cars and two drivers.

It would make sense if I was a business who had hundreds of cars or some other weird corner case perhaps, but regular people who could afford to post a bond have a better option in the insurance market.

It makes no sense to self insure like you said. You would get totally screwed in any split risk decision