Over 85 children have died or suffered severe brain injuries involving
automatic garage doors since 1974.


Between 1974 and when? Given a ten year span for that figure
(74 to 84) that puts the risk at less than 1 in 30 million
per child per year. SInce you can only be a child for
about 15 years, that means the risk per individual is around
1 in 2 million, which is well below my threshold for alarming
risks.

If you make a set of assumptions designed to justify
the detectors, (the detectors prevent 75% of such
accidents, somewhere in the vicinity of 8 million
relevent garage doors in the country), you could
expect, at best, a 1/125,000 chance that any given
installation will prevent an accident.

If the things add $20 to the cost of the door, then
it makes sense to add them if you can't save
more than one life by spending 2.5 million dollars
somewhere else.