We do a lot of cement driveway resurfacing. What he's talking about is when the concrete gets worn after years of weather, it just starts looking bad. Back in the early 90's there were several companies that came out with these supposed miracle products that they said you could just spread over the driveway and it would "resurface" it. Problem was, the stuff cracked after sometimes just a year of cold weather and vehicles running over it.
When we resurface, we will actually find the cracks, cut lines in the cement and drop stainless steel 10 inch staples into the concrete and then cement around it to stop any further cracking. Then we will run a layer of flexible resurfacing concrete over the surface and this seals it. You can even trowel it and make it look like a new driveway was put in. The new technologies have more flexible surfacing and it doesn't crack like what you are talking about here. We can actually offer between 5 and 15 year guarantees on our resurfacing depending on the volume of traffic over the area.
The problem you are going to run into is if you try and resurface it again over the old stuff you run the risk of the old stuff coming up. Unless you are going to resurface it for them, I would do this on a time and material charge and rent a low power jack hammer or asphalt compactor to crack the rest of the material away.
I'd think about resurfacing it for them though. It's not as hard as you think. Just make sure you get rid of the old stuff first.
