Public CAs are not that type of people; I would be disapointed if that were not running two seperate systems checking each other for consistancy; having top of the range ECC running well inside its specification must be table stakes.
Not hundreds. There are currently 52 root CA operators trusted by Mozilla (and thus Firefox, but also most Linux systems and lots of other stuff) a few more are trusted only by Microsoft or Apple, but not hundreds.
But also, in this context we aren't talking about the CAs anyway, but the Log operators, and so for them reliability is about staying qualified, as otherwise their service is pointless. There are far fewer of those, about half-a-dozen total. Cloudflare, Google, Digicert, Sectigo, ISRG (Let's Encrypt), and Trust Asia.
[Edited, I counted a column header, 53 rows minus 1 header = 52]
