What you write seems more to do with Vanguard making sure my account information is correct. I'm wondering how my bank allows a transfer TO Vanguard without my ever giving explicit permission to the bank to do so. And by extension, couldn't anyone who knows the routing and account numbers initiate a transfer to them?
This shows up often on this forum. My understanding after reading some knowledgeable poster is that only the fear of landing in federal prison prevents somebody from pulling the money out from an account whose routing information is known.
For example, if you wanted to pay your kid's Harvard tuition, just remember the information from Neurosphere's check that you had received in the past. If you enter that information, the money will be taken from Neurosphere's account. It is like getting a free ride to Harvard for your kid! Once investigation is completed, your will become guest of the Uncle Sam for few years
Many many entities such as universities, local town offices, mutual funds,utilities etc allow you to enter accounting routing details on their system which will PULL the money from your bank account for the payment. Absolutely nothing in the system safe-guards against intentional mischief.
The bottom line:- There are ZERO technical hurdles in pulling the money out of your account once the numbers are known.