Google Support – Trash says:
Anything you remove from Google Drive will be in your Trash until you permanently delete the files or restore them.
However, they are known to be loose with words, and Google's support documents aren't meant to be elaborate (read as literal).
Is there more information regarding this issue?
Can we count on items in "Trash" to be still recoverable after a few months/years?
Best Answer
No, it will not be.
Source.
Also, yes, the deleted documents can be recovered for a limited period of time and only by request.
Source (under Recover a deleted file).
However, there are some scripts that can do that. See this question for more information.