可能是那人买的是州法规定的最低的个人伤害保险，你们德州好像就是如此，

“If you buy insurance to meet the state's financial responsibility law, you must buy at least the minimum amount. The current minimum liability limits are $30,000 for each injured person, up to a total of $60,000 per accident, and $25,000 for property damage per accident. This basic coverage is called 30/60/25 coverage.”

http://www.tdi.texas.gov/pubs/consumer/cb020.html