No incentive, right? If you mess up as a CA, you go out of business because every browser drops you. But if you're an identity provider and you have an incident, maybe 1% of your customers opens an angry support ticket and you give them 5% off their bill next month. So why bother? Are YOU going to move your 100,000 employee organization off of Microsoft because of this? No? Then why would they care at all? They won the sale and you're stuck with what you get.
Here's a list of companies that have gone out of business because they didn't take information security seriously:
<list not found>
Here's a list of billionaires who had to sell their yachts because they didn't prioritize security over other concerns:
<list not found>
Yeah.