if you were using google drive to store images (e.g., you automated a camera system to take high res pictures), you can easily reach this limit.
Of course, it definitely is much nicer to have S3 over google drive for such a solution, but if you didn't want to write software (which you'd need for S3), and simply used the google drive's sync'ing features...
In this case you can just delete the oldest files, or tar/zip them in to one file. I doubt anyone needs instant granular access to 5 million images.
The chance of hitting this limit is so insanely slim and the workarounds are so trivial that I don't really see any issues here. I bet there would have been some abuse where someone tried to store data in file names and metadata which is not counted to your quota.
