I don't think it's ideal that to someone unfamiliar with how BTC works, looking at the display it looks as though the minimum spend is ~$480. A little display underneath with $1 = 2085 uBTC/bits would be good, just to clarify that you can put 20 bucks in if you want
I think it is clear to me that the display is saying what the price of 1 bitcoin is, and not the minimum purchase amount. I would think it should be obvious to the public that you can have/buy smaller amounts of bitcoin then 1 BTC just like you have have small amounts of "dollars" just like pennies, nickels and dimes (ect.) allow.
I also know that many bitcoin ATMs do a lot of volume so I would speculate that average transaction size is a lot more then $20
