Topo data isn't correct either for elevation gain and loss. You can go up and down many times between the contour lines on a map that represent 10 feet of elevation.

That's part of the issue for all of us users. What do we count as elevation gain and loss? If I go up and down 5 feet twenty times then shouldn't I get 100 feet of gain/loss? If I don't cross a contour line on a topo, then I didn't gain anything.