Emily plays on mine. Sometimes for fun, sometimes educational stuff. She's always supervised though and Google require I put my password in for purchases also. When she had that cheap Chinese tablet I installed an app (can't remember the name) to lock it down in a kid friendly mode. That was pretty cool.

Yes an option to lock it down to a child friendly version where all in app purchases are not even allowed to be displayed would be a very good solution.

My smartphone is a company phone, so nobody could legally use it anyway (data protection).