Sometimes that doesn't work either. I had to cut a parking lot and replace a bad underground conduit. The customer was to have a paving company come out afterwards and properly compact and re-pave. It was a main drive, so it could not be blocked off. Three weeks later the customer calls up raising Cain about a customer damaging their car because all of the truck traffic had compacted the gravel further, and when it rained, it filled up the hole. The driver was haulin butt across the parking lot, and hit the new pot hole. Even though the customer failed to re-pave in a timely manner, we got stuck with the bill.
There's no way you get stuck with the bill if you have a properly worded contract.