Lemurian -
Two of the accidents you listed were the (apparent) result of PILOT ERROR. The fact that the spoilers are 'mechanical' really did not matter.
05 July 1970
Air Canada
Toronto, Ontario, Canada
60 feet above the ground during landing, the speedbrakes were inadvertantly deployed by the First Officer, which resulted in an excessive sink rate. The no.4 engine struck the runway, and a go-around was initiated. The aircraft proceeded to climb out normally, but while on a downwind for a second landing attempt, the aircraft exploded. Ruptured fuel line during the first hard landing.
28 November 1972
Japan Airlines
Moscow, Russia
The aircraft crashed on takeoff after the accidental deployment of the spoilers by the Flight Engineer.
"OK, I'm out of here.
Technical discussions are alright, but this is turning to a dialogue of the deafs...my fault, I suppose."
OK.....have a good day.