I thought you had no choice but to purchase health insurance. If you did not then you get the penality (tax). So why the push to encourage people to sign up, let the law run its course.
Because the penalty is a pittance in the early years. It's like the threat of getting a $2 ticket for speeding. The problem is that insurers have a maximum age differential they can legally charge which is a lot less than the actual differential cost, so the healthy young will be expected to pay much more than their expected medical costs. Unless they have a preexisting medical condition it makes sense for them to just pay the fine.