I wonder if AWS billing still uses CSV files for passing data around.
IIRC it was one of my first on-calls at AWS over a decade ago now, and I got a page early evening because some stuff we did with billing records broke because some "smart" engineer thought it'd be a great idea to put an experimental record in with a description something like "I wonder what happens if I put, a comma in this field", into the production record. I watched region after region fail the same way as the record spread. That one engineer made a mess of lots of people's evenings. They could have used the test endpoint, but no. Much better to test in production!
IIRC it was one of my first on-calls at AWS over a decade ago now, and I got a page early evening because some stuff we did with billing records broke because some "smart" engineer thought it'd be a great idea to put an experimental record in with a description something like "I wonder what happens if I put, a comma in this field", into the production record. I watched region after region fail the same way as the record spread. That one engineer made a mess of lots of people's evenings. They could have used the test endpoint, but no. Much better to test in production!