Mike, believe it or not I've actually purchased food from one of those. In fact they're still in vogue in Japan, or at least they were the last time I was there about 5 years ago.
Rick, sounds like your wife might not go for this but here's what my wife and I do, which pretty much eliminates the problem you explained. We have one credit card account and one debit card. The credit card is used for most purchases and it's paid in full every month so we never pay any interest. (In fact we get cash back but that's another story).
The debit card has one use only which is to obtain cash from the ATM - "walking around" money for incidentals. When we make an ATM withdrawal we split the cash 50/50 between us (then she runs out and "borrows" mine).

The checkbook stays home and is rarely used. Neither of us carry a checkbook or any checks.
The bank and the credit card company both provide an "alert" system for which you can enroll and set your own alert limit. Any purchase or withdrawal exceeding the limit you set triggers a text message to my cell phone within minutes of the transaction. I can also send the bank a text 24/7 requesting our account balance and receive a response within seconds. Both the bank and the credit card company have on-line apps through which you can log in 24/7 and see all up-to-the-minute transactions and account balance - makes it really simple and easy to keep track of everything.
Don't need checks for anything except paying a few monthly bills.

when either of us want to know the "balance" the answer is available within a few seconds. None of this is difficult to set up and use assuming you have an Apple or Android system on your smart phone.
Ken