The odd thing is, why doesn't it work from iOS 7 to Mac? Same function, right?
Yeah, only Mac to Mac, and iOS to iOS.
"OS X and iOS use different AirDrop protocols and are currently not interoperable.[1] AirDrop in OS X operates over Wi-Fi, whereas the iOS implementation utilizes both Wi-Fi and Bluetooth."
http://en.wikipedia.org/wiki/AirDrop
In both cases, AirDrop uses wifi direct, a hardware option only found in the latest Apple devices. In the case of iOS devices, they also need to have low-power bluetooth (4.0). (iOS 7 uses BT to find others and connect. Both use wifi direct to securely transfer data (& puts up a firewall on both sides), no network connection needed.)
for iOS: "AirDrop is available on iPhone 5 or later, iPad (4th generation), iPad mini, and iPod touch (5th generation) and requires an iCloud account." taken from footnote 5:
http://www.apple.com/ios/whats-new/#airdrop
As far as between iOS & OS X: I am sure this is a temporary situation. Apple would not have used the same name and not make it compatible between iOS & OS X. However, they may not implement it before iOS 8, even though, I'd like to see it in iOS 7.1
. ...But, I think the OS X end is where a change might need to be made to connect to iOS 7 AirDrop.