"Unless such failures are extremely remote"
That leaves a lot of wiggle room for the builders I think.....and just how does one define such events as being "extremely remote"?
This reminds me of the US airlines arguing Boeing 727 flights from New York to Miami did not require life rafts and other "over water" safety items as the probability of a ditching being required was "quite remote". The wonderful FAA agreed.
Less than two weeks later at the most inopportune location.....some halfwit FE managed to flame out all three engines by mis-managing the fuel system. The crew very fortunately were able to cure the problem and get the engines back on line but came very close to the water while doing so.
The rafts, jackets, etc......were re-installed shortly thereafter.