If you were to be involved in an accident while driving your truck for personal reasons, an injured party would likely bring a suit againt you AND your carrier because your truck is branded with their logo. It's the American way, sue the deep pockets.
In this day and age, $1 million is probably a good figure to protect you and your personal assets; some carriers require $2 million non-trucking liabilty. I believe they require you to have this much to protect themselves more than you. Your large limit just might keep the wolves from their door. Although this large amount of insurance is required as a condition of the lease agreement to which we agreed, I think it inappropriate for the carrier to require this large amount. It is not unlike Freightliner requireing you to have a large policy because you are driving a truck which, if involved in an accident, might subject Freightliner to litigation.
Enough venting. to answer you specific question: Yes a million dollar policy is common in the expedite industry.