That does sound expensive unless your son's only 17, in which case it'd be a bit of a bargain. By comparison, I pay 'A Plan' under £100 for 3,000 miles comprehensive cover for my 2 litre straight six powered Spyder.
If it's not your son's age, I'm guessing the issue is either the perceived higher fire risk from the batteries or just the unknown quantity factor of an alternative power source.
Out of interest, how much did the electric conversion cost (minus any body/chassis/interior restoration costs)?
Nice job, btw, I take it it's this one?
https://www.youtube.com/watch?v=FhWiX8iCX6g
That clip does highlight one potential 'issue' with electric cars though - far more torque than traction. I wonder if a Panda 4x4 or (original) Subaru Justy could be converted? Now that
would be fun off the line at traffic lights...