I am not aware of any vendor or bank that purges order or transactions after 24 hours. Amazon keeps years of purchase history, and even some history of what you looked at.This has been an issue with backup/business continuity service providers since at least 2000, when I first got involved. There are lots of ways you can timeout a backup so that you don't maintain confidential information in the backup set. In almost all cases, businesses maintain a backup of their transactional data only for business continuity purposes, which means that they only care about the most recent 24 hours. They normally shouldn't bother to maintain any significant history, since it's not cost effective. In respect to other files (like email messages or word documents) the good backup systems give you rules you can put in place to ensure that when data is purged from the online data set it will automatically get purged from the backup sets (note purged is different from deleted). Any business that claims to delete your confidential info that doesn't have one of these systems in place is effectively lying to you.
Ant to what extent can a subpeona force a business to go to try to recover data? Can it mandate stop of writes to the drive with the data followed by use of deleted file recovery programs? I'd guess that there is LE software that has features like scan contend of deleted files not yet overwritten. This is harder on Unix/Linux since the file systems on Unix tend to overwrite recently freed space, whereas NTFS does the opposite leaving a very long history of recoverable deleted files.