Eli5: Why were the Boeing Max 9 planes immediately grounded but not the Max 8’s?

Question

I don’t understand why regulators immediately grounded the Max 9’s, but it took two Max 8 crashes before they were grounded.

In: Other

Answer 1

With the Max 8 crash, it wasn’t immediately obvious that the issue was with the planes design/software.

With the Max 9, they have pressure from the Max 8 crashes as well as what is very obviously a hardware issue.