ACH is used either to get paid by an employee or to move money between accounts, neither of those things are that easy to do with Venmo, in fact zelle was created to compete with Venmo and it addresses that competition so nicely that many of my friends have moved to it.
Not sure I agree. How about the incentive to prevent customers using competing services like Venmo and others?
Also the incentive to quickly receive funds into bank coffers so the bank can lend it faster.
Presumably, increasing the ACH batch frequency would break something in the system or it would already have been done.