Behind bulletproof glass, a smiling teller at a RiteCheck store in the South Bronx waited patiently for customers to hand over their checks. For every $100 cashed, she collected a $1.91 service fee.

Bills to pay? She handled that, too, for $1 per bill.

“Anything else, honey?” she asked one of her regulars. “O.K., have a nice day.”

Many of New York City’s poorest residents do not have bank accounts, so these window transactions, repeated hundreds of times every day, are their primary contact with the financial system. Check cashers are as familiar to them as corner bodegas, and as reliable.

But an industry built on mutual convenience has come under increased scrutiny over the past decade as its stores have continued to become full financial centers, improving services like electronic bill payment, wire transfers and prepaid debit cards.