~10x as dangerous checks per km checks out if you assume the same distance is traveled either case. (1 fatality per 100k flight hours * 200KPH would be 1 fatality per 20 million km.)

However people who fly regularly tend to have crazy high total mileage compared to the ~15k miles/year of a typical American. Which is why so many general aviation pilots die relative to car crashes, it’s just inherently a very dangerous hobby.