The graph is good but doesnt factor how many of each age group are on the road. Theres probably ten 17-25yr olds to every one 75+yr old.
Not to mention time spent on the road. I would easily do 30,000km per year. My 72yo Father would struggle to do 10% of that.
The noticable drop between 46-55 (kids grow up and start to drive themselves), 56-65 (more kids grow up, start of retirement) and 66-75 (retirement) would demonstrate this.
Also as you get older you reduce your exposure to driving later where drunk/drugged idiots are highest, and the fatigue of working/raising a family (and associated taxi work) and trying to have a bit of time for yoursef can really impact.