The funny part about this is that they actually took the right approach from a security standpoint. Making people prove they are trustworthy before they are allowed in the playground is a type of "white listing" based policy. White listing is a far superior approach to the typical "black listing" approach of relying on registries of known perverts that need to be kept out. If we were truly interested in mitigating the risk of pedophiles coming into contact with children in a public park, the approach they chose is, in fact, the correct one.

What this shows is not that they are going about things the wrong way; they are not, this truly is the right way to go about mitigating that risk. What this actually shows is that the costs of implementing proper security measures to mitigate that risk far outweigh the benefits and thus it is a risk that should simply be accepted. When your children are in public, they are likely to encounter pedophiles and it's a risk you need to be aware of and take into account at all times rather than attempt to mitigate it. Mitigating it just isn't worth it.