You might as well ask why Wall Street doesn't prefer trains with 3 cars and 1 loc. Much safer - but not optimising their profits. A guy who hitches a 4th car beats everyone.
So trains are optimised for profit. Now if your trains never derail, that means you may still have safety margin. There may be profit for the taking!!!
So keep optimising till it goes wrong. Then, figure out the cost of "going wrong". Figure that into your margins. If you get 99% delivery with 110% profit, does that beat 100% delivery for 100% profit?
TL;DR: that's how free markets work in capitalism. They optimise for profit.
So trains are optimised for profit. Now if your trains never derail, that means you may still have safety margin. There may be profit for the taking!!!
So keep optimising till it goes wrong. Then, figure out the cost of "going wrong". Figure that into your margins. If you get 99% delivery with 110% profit, does that beat 100% delivery for 100% profit?
TL;DR: that's how free markets work in capitalism. They optimise for profit.