That was just a massive operational failure, not the fault of any single engineer. No change, except hotfixes, should be able to land on prod unless it has at least go through test, staging, and at the scale of Amazon, shadow testing.

Engineers will do what engineers will always want to do, they want to see how things break, and sometimes they manage to fix it.

CSV files are widely known to be used by the most frugal companies so of course it is.