I think the "nearest service center" is pretty standard. I have tow coverage on my auto/mcyl/MH policies. When my daughter broke down on the way home for the holidays she was within 10 miles of several service centers. But, I wanted the car towed home 30 miles to my guy. Insurance only paid a portion. My local agent cut me a check himself for the difference.
When my motorhome broke down I was only 15 miles from a service center, but the nearest tow company that would touch it was 50 miles away. My insurance picked up the whole $750 tab to the nearest service center, including the extra mileage for the tow company to get to it.