For me it's a combination of consistent speed and being able to not care about inclines at all. The safest bike route to work for me is ~2 miles longer than the optimal route and includes a steep incline. This is a pain on a regular bike, but no big deal on my ebike.
Also with an ebike you are almost never going slow. Accelerating to cruising speed usually takes a couple of pedal cranks, not a full city block.
I live in Seattle and there are a lot of hills when going east/west because it's a glacial area and the glaciers come down from Canada north/south. Fun!