When spares were first put in with cables and hoists, there were lots of reports (and resulting lawsuits) of spares falling due to cable breakage. All were from rusted cables. Shortly after, car makers started using stainless cables to replace those as well as using them in all vehicles after that. I do believe recalls were issued for this. Haven't heard anything since then (late 80's early 90's) about falling spares. My 08 Montana has an under mounted spare and doesn't have a secondary latch, just the hoist cable. Our trucks also use stainless cables. I think GM was being (surprisingly) over cautious because it's a full sized spare. Only reason for replacing them is people continuously turning it while the secondary latch keeps holding the spare, destroying the cable. I have absolute confidence with having the tire upside down with no secondary latch.
Dorman decided to use regular rust prone steel cables in their replacement hoists, which was the reason for me to not recommend them, especially since they removed the secondary latch. I can see lawsuits for them in a few years.
Toyota are recalling 04-11 Siennas because they tried to go cheap with steel cables and is now rearing its ugly head. They first tried to use some sort of splash shield and rust inhibitor for the cable but that didn't work. So much for Japanese quality