Is there any way for us to know if one of our end customers have set up direct deposit?
Unfortunately, there is no way to verify this. The end-customer usually needs to provide a Direct Deposit form to their employer, Government or Payroll provider with the account information to process the deposit.
You can assume that if a end-customer has requested a Direct Deposit form they are going to give it to an employer, but this is is not guaranteed (i.e an end-customer can ask their bank for a Direct Deposit form but decide to use a different account for their payroll because their second bank gives them a better incentive or their payroll provider cannot recognize that institution)There are solutions in the market to switch existing direct deposits payroll like Pinwheel or Atomic which you may find interesting.