There probably was an internal tool, but it was also probably too complicated and convoluted to use. I don't work at DOJ or the Senate, but at my agency (NASA)

There probably was an internal tool, but it was also probably too complicated and convoluted to use. I don't work at DOJ or the Senate, but at my agency (NASA) there is a "large file transfer tool". It requires an obscure login with inane password requirements (and short expirations, so passwords expire more often than people probably use the tool), and the site can only be accessed from behind the firewall, making it useless for sharing files while on travel or with contracting organizations and collaborators at universities. The result? Nobody uses it. Thankfully the organization I work at has our own security plan, so we created our own large-file tool that was easier to use. Before that people would give me (the web developer) a file to upload to an obscure URL on our web server, since that was easier and more reliable than dealing with the approved NASA solution. If I wasn't there I could totally see them using megaupload or something similar instead.