Kriss, a lot of braid breaks over, and mono too.
As for reasons it overtests so often, so badly, I have been offered the theory that because braid knots are a lower percentage of the line's breaking strain. Its not totally unrealistic either, the thinner the line, the worse the problems are with most knots and certainly one reason why a good braid to mono knot, then terminal is tied off to mono.
You generally fish about a third of line strength as drag, and your terminal knots are usually about 65% of line strength. That means on say 10kg gear, you would be pulling 3.33kg of drag out the guides, and your knots would breat at about 6.67kg. The gap between the drag setting and your knots failing is insurance and helps account for other issues, like the drag increasing as your spool empties etc.
Fishing 1/3 of line strength as drag is a rule, and rules are made to be broken. You might get really good knots and decide to fish more, you might move to jb hollow and uses 100% fingercuff splices and crimp!