To the first question:
This is a statement that
absolutely requires evidence to be taken seriously in any way...and it contradicts the following:
In addition, your statement about what "would" happen if seatbelts were [required to be] installed on school buses is obviously straight out of a rectum, though if you have evidence I would love to see it.
Finally, I can assure you that I do not consider you a friend.[/QUOT
Not friends, but friendly.
Those are both valid ways to look at costs as long as you dont double count.
The seatbelt example is extremely common in discussion of opportunity costs. Here was the first link googling the debate.
http://abcnews.go.com/US/putting-seatbelts-school-buses-save-childrens-lives/story?id=28594633
Here is a key quote
"In addition, the agency has maintained that mandating seatbelts would have unintended consequences. The costs involved in outfitting buses with seatbelts, NHTSA has said, could reduce the number of buses available and wind up diverting more students into passenger cars, which they say would increase fatalities and injuries on the road."