ATM is a bit of a misnomer isn't it? Can you deposit gold into your "account" at the machine? If not then it's similar to any other sales kiosk (like the ones at the airport selling headphones)
Any ATM attached to a bank does let you deposit, actually. In the states, mostly just in envelopes that are counted later, but in China, they actually count and verify the money in place.
I would imagine that there are more ATMs unattached to banks than attached, so saying "most" ATMs don't take deposits doesn't seem like a stretch to me.
As for deposits, modern ATMs in the US will count bills and also scan and deposit checks immediately without envelopes.