The simple answer is because Intuit doesn't know how to write software properly.
Think about it.
Microsoft Office can update without an admin having to run the updates (any user can open Word, go to File, Accounts, and check for updates).
Microsoft Edge, Google Chrome, Firefox and any other browser that I'm aware of can update automatically.
Adobe Acrobat updates automatically. And the list goes on.
Many applications have a "check for updates" option that can check for and install applications without the need for an administrative user.
And yet, somehow, QB's developers haven't figured this part out.
And so their fix is to either make systems less secure as many companies will take the easy way out and let users run with administrative privileges so that they can work when they need to or to force users to have to stop and get an admin to update their application.
Very poor design.
