Never Change

My local drugstore has an automated checkout.  As soon as I pick the option to pay with cash, the computer voice says something like "insert coins first, and then bills."

First time I heard it, I wondered why the machine would care what order the money comes in.  But after thinking about it for a second, it's clear there's a reason.

Once you've paid the bill, the machine gives you change.  Now with a human cashier, if something costs, say, $5.33, you might hand over a ten dollar bill and then a quarter and a dime.  But that wouldn't work with a machine.

Once you put in the ten dollar bill, it recognizes you've paid, and won't take any more, but will give you change.  So the programmers decided we need to be told to put in whatever coins we might use first.

Should I admire the efficiency, or be offended for being thought so dumb I can't figure this out?