The micro-deposit requirement or Plaid (logging into the bank account) should ideally minimize fraud. But for consumers ACH fraud is sadly way more difficult to deal with than credit card fraud.
It is quite easy to get access to high value checking accounts for less than 50 USD. They could be personal or business. For between 25-75 USD you could get access to all the login information you need to access Wells Fargo/SunTrust/BoA accounts. You could see both Plaid micro-deposits. Even PayPal has faced this issue and they're solution was to be a huge pain in the fucking ass to users.
Balancing convenience with security for ACH is not an easy task. That's why ACH is so damn hard to do online.
