I think "younger" here is meant more as "not old." 16 year olds are less safe drivers, yes, but on account of the price they're not going to be a big part of Tesla's demographic.

Since there's no affordable model, and they're a newfangled gadget with strange refueling infrastructure and a giant touchscreen for a console, Tesla owners probably skew toward middle aged. So they'll have fewer drivers in the less safe age ranges at both ends of the spectrum.