I like it too because those in situations to have a lien filed is pretty serious IMHO. It's not a matter of ignoring IRS notices for a few times.
Ironically enough I formed this opinion due to my own history. I acutally didn't file returns for three years (dealing with job loss and depression), and I got so many notices from the IRS and several chances to make it right. And when I filed and it turned out that I was due a return on two years, the IRS paid that amount and if I remember correctly the IRS even waived the penalty for not filing. Basically if you get your sh*t together and deal with the delinquencies even after a long time, you don't go near being threatened with a lien so I can only imagine how the people must have responded or not acted to actually get liens. I remember thinking that the IRS was surprisingly lenient in terms of giving plenty of time and chances to respond (or argue your case if you disagreed with the IRS numbers).