> With other factors being equal, addresses in less affluent ZIP codes with higher minority populations were quoted annual premiums that were $410 higher, on average, than those in neighboring ZIP codes with wealthier, more heavily white populations, according to the analysis.

and from the linked study, these are minimum liability rates, not comprehensive:

> Except for the address, the tested drivers were exactly the same in every way, and the coverage is for the state mandated minimum liability policy.

(Add in what happens to a low-income family when their new-to-them $2k, minimally insured Corolla gets totaled in the first week to the "things that make it expensive to be poor" list, too.)