Mechanism One
The merchant fee gap: gross in, net out
Sell a $10,000 system, take payment by card, and ServiceTitan will record a $10,000 invoice and a $10,000 payment. Your bank may receive $9,700. The processor kept roughly three percent, and it kept it before the money ever crossed into your account. That $300 is a real business expense, but nothing in the ServiceTitan export creates it. There is no line for it, no bill, no vendor.
So QuickBooks believes it received $10,000 and the bank statement shows $9,700. The reconciliation is off by $300 on that one job. Multiply that by every card-paid invoice in the month and you are trying to reconcile an account that is structurally wrong by thousands of dollars. Nobody made a mistake. The system simply never recorded the cost of getting paid.
Where the money usually ends up hiding
When the fee is never booked, one of three things happens, and none of them are good. Either the deposit sits in the bank feed unmatched and the account never reconciles, or the payment stays stranded in ServiceTitan Undeposited Funds forever, or someone forces the deposit to agree with a manual adjustment and the difference quietly lands in a suspense account or, worse, gets netted against revenue. Netting the fee against revenue understates your top line and hides one of the largest controllable expenses in a high-ticket trade.
Merchant fees on a shop doing meaningful card volume are not a rounding error. At roughly three percent, a company running $6,000,000 through cards is spending real money on processing every year. It belongs on the P&L as its own expense line, visible, so you can see it, negotiate it, and decide whether to steer more work toward financing or ACH.