There is a trend in Germany right now, where police ask whole neighborhoods for voluntary DNA testing when they are looking for someone. The problem is that you'll get a visit and asked why you didn't volunteer if you don't go.

And it looks like it's not just Germany: http://news.bbc.co.uk/2/hi/americas/4161983.stm

I think part of the problem is that the reasonings in these cases aren't out of this world. So people will think of the whole issue as much less problematic.