There really isn't a way to avoid these fees. Years ago there was the unpublished Hertz transfer desk which would waive the one-way fee for "repatriating" a car to its country of origin, but few if any FTers have successfully used it. Similar to the experience you're describing, I guess, but you'll never know if that opportunity exists ahead of time since inventory changes constantly.

If anyone's had a different experience, I'd be VERY interested in learning about it.