You can be sarcastic but there is no reason you've said why emails and documents of a few megabytes can't be permanently saved by companies using Exabytes of data. Make your point
Apparently it's way too hard and complicated for a multi-billion dollar enterprise to retain documents but quite easy to tell clients how to evade taxes.
What a fucked up world.
Understanding the intricacies of large enterprise data and all the forms it can take is an exercise left to the reader. It isn't simple and I'm not sure why anyone would think it is. There isn't just like, a single fileshare you have to monitor. There are many more numbers than just X amount of data.