My 600 Lb LIfe-Penney my first time seeing this episode

Actually, I think they screened many people and Penny was picked because they needed someone exactly like her.  If everyone picked was compliant and lost their weight, the show would be less interesting.

A Penny shows the public the type of people who have surgery, but change nothing in their lives.  There are many "Pennys" out there and she gives the series an interesting dimension.  We see successes and failures and that make the show much more real.

You make a very valid point.