Because you don't use gmail? Because your target doesn't use gmail? Because you're already a square user and not a Google Wallet user? Because you'd like to use a debit card without paying a fee? Because you like the letter S better than you like the letter G?
I'm pretty sure Google Wallet in Gmail lets you send money to someone not using Gmail. But you are correct. I guess it's a good solution if you don't want to deal with PayPal/etc. when you happen to use your own email setup or Outlook/Yahoo/etc.
It has nothing to do with being edge-cases like "if you're hosting your own email thing". Personally, I just like to limit how many of my eggs are in one basket, and I already have a lot of eggs in the Google basket. I like my bank's own built-in system for this right now between me and their other customers, and for everyone else I use venmo. It works great, and I have no real complaints about either system.
But really I don't need to be talked out of using Google's like it's the default, and I'm not clear on why you do. I don't really get the "why do you use your own favourite toy instead of my own favourite toy?" crowd
Not true. We only charge the sender to send from a credit card. If you send from a bank account or from the funds that you've already received, it's free.
Thank you for clarifying! Looked further into it here [0] "Receiving money is free no matter what." However, the text "You can add other payment methods like credit and debit cards, and a 2.9% fee per transaction (minimum $0.30)" is still a bit unclear.
The products are marketed very differently and have different features. Google Wallet is explicitly hoping to replace your wallet, focusing on loyalty cards, NFC payment, online shopping, and fraud monitoring, in addition to simply sending money to friends.
On the other hand, Square is positioning Cash as a dead-simple way to send money to friends, whether or not they've download the Latest Social Micro-payments App™. Its plumbing. Long run, they are obviously gunning for cards-on-file to support their merchant tools, where they make money hand-over-fist.
Who knows...Square Cash might expand into something that resembles what Google Wallet is today. They seem to be starting with the basics.
Besides that, Google Wallet is available in all 50 states, while Square does not allows residents of Hawaii and Tennessee to send money (only receive it).
It's still in slow rollout stage. If you want to try it now, I'll send you a cent and it should be enabled for you. (You must be in the US, read the TOS, etc.)
http://www.google.com/wallet/send-money/