By making a rule that the child must give you the device whenever you ask for it or their phone privileges will be revoked. There is no other way to read actual text messages, however you can check on your bill to see the number and at what time phone calls and text messages are being sent.
The difference in Family Base is it supplies the name of the contact and a time stamp, unlike the bill which provides the number and time stamp. Family base also puts a nice little bow around everything; breaks down number of text messages in an easy to follow format. However if your kid uses other messaging services like KIK or iMessage you won't know.