I think the Flintstones -style dialogue below is going on between the machine and the bank's computer.

When account is full of cash.

ATM: Yo, J.P., hey, does this guy have cash? He wants $40.
Bank : Hmmm... oh, hell yes and plenty enough for your Starbucks-coffee-priced ATM-fee cut. Grab it on the way.
ATM: Hey thanks, getting it right over.

When the account is in double digits:

ATM: Yo, J.P., this guy got $40.?
Bank: Hmmm.....I don't see much in here.
ATM: He's waiting.
Bank: As well he should, this well is really dry. Let me double check. Maybe he's got some checks out too I can put a bounce fee on, the loser.
ATM: Standing by, and don't forget my fee.
Bank: Yeah........{micrmoments stretch to real moments}....oh, yeah he's barely got it. Must need it for a late payment.
ATM: Should I kick it over?
Bank: Guess we got to, you're covered too, but do me a favor.
ATM: What?
Bank: Make him sweat it.
ATM: Sure thing. People like him holding the richer ones up, I'll show him. Loser.
Bank: You know, I wish I could charge a "bounce" fee and then give it to him.
ATM: Only my retail brothers can do that for you, and boy do they!
Bank/ATM: {cackle hysterically}
Bank: Well, I gotta dock the account lower...... if that's possible. {guffaws}... Hey, you should see his last paycheck.
ATM: How bad?!
Bank: Can you say "temp"?.....Here's your cut.....Did you fork over to him his --pffft -- treasure?
ATM: Oh, yeah, almost forgot to do that. .. But you know what? I've been running the cash dispenser motor for like 20 seconds now. Look at him jump, look at him jump!!
Bank: Oh, I wish I could see that.

Of course, I know the above doesn't happen.

But we all know it does.