People taking the law into their own hands with debt collecting

Probably because they've let anger get the better of their good judgement. Clearly the incidence outlined is outrageous and the culprits should be pursued criminally.

There are more subtle ways of collecting debts which yield better results without exposing yourself to criminal prosecution or the grind of the legal system which, in many cases, will mostly leave you with a judgement but no way to collect.

I could quote some examples but then I'd be giving the game away, eh!?