Carrier has cargo insurance with mandatory $100,000, but usually around $250,000-$350,000 per accident (not per car).
When multiple cars damaged this amount is split, largest truck takes up to 9 cars.
Primary payee is cargo insurance of the carrier. Secondary Payee is your insurance if you have physical damage on your policy.
Check if your insurance policy has physical damage/subrogation for your car.
You can also add physical damage to your policy today, then remove it after car has been delivered.

You don't need your car insurance to have your car transported.
But without physical damage/subrogation you will have to collect from carrier's insurance yourself and it's a pain.
With physical/subrogation your insurance company will make it much easier for you because they will collect from Primary Payer (carrier's insurance) first, then if it's exhausted come as Secondary Payer if needed.

99% of the time you sign contract with broker company, then broker company hires carrier - transportation company with trucks.
Auto transport broker has bond of $75,000 that is for broker's wrongdoing only, it does not cover your car from damage in transit.
Carrier has mandatory $100,000 cargo (usually $250,000-$350,000) insurance that can be split between up to 9 cars that fit on Stinger Truck (like on picture above) or 7-8 cars that fit on high mount trailers, or less cars for smaller trucks.

• Find Car Title
• If you have policy with physical damage/subrogation - file to your insurance (easy)
• No physical damage on your car insurance - file to carrier's insurance (hard)

1. Party at fault or their insurance, liability coverage
2. Carrier's insurance, cargo coverage covers your car
3. Your Deductible
4. Your Car Insurance, physical damage coverage

Brokers verify carrier's cargo insurance, insurance also required for many of compliance steps for trucks,
and it's monitored by RMIS which notifies brokers about changes - you can be pretty sure that all carriers taking cars have an active insurance with cargo coverage.
Insurance does not cancel instantly, it is either expires at the end of term or pending cancellation for 30 days before it becomes inactive. We have carrier's certificates of insurance and can email you a copy - just ask.

You can check if broker's bond and carrier's insurance is active on government web site - FMCSA
Once located company check if USDOT status "ACTIVE", then click on "Licensing and Insurance", then button "HTML".
It shows liability but does not show cargo insurance correctly - that section of the page is broken.
Then click "Active/Pending Insurance" to see if it is pending cancellation.
This page has insurance company and policy number if you need to file a claim.