It is true that technically people can process a payment or deposit against any account where they have the Routing and Account number. However, the legal cons

It is true that technically people can process a payment or deposit against any account where they have the Routing and Account number. However, the legal consequences of doing an unauthorized withdrawal is quite stiff, not to mention the audit trail is really easy to follow. And your own bank will provide fraud protection if someone does this, limiting your liability to basically nothing. I generally have no issues giving a company our wire information or ACH information. I'd much rather get the fraud protection from my bank. The difference to me is this. My bank sides with me first until the other side proves they were authorized, e.g. within 24 hours they put the money back in my account and fight with the other side to prove they had my authorization for the withdrawal. If you get a chargeback or Paypal refund, they both side against you and make you prove you were entitled to receive the funds, and even then many times won't care (Paypal).