Leaving vital cash tied up in unpaid debts doesn't make business sense. Many of the debt collection agencies just collect the easy ones and then refer the tricky ones to the defaulter's list. Whilst this may warn the small percentage of traders who carry out credit checks that your debtor is not credit worthy, this doesn't get you any cash.
We can take positive and pro-active action to collect your cash by either:
Initiate winding-up or bankruptcy proceedings where the debt exceeds $1,000
Court action to obtain judgement on your behalf
You will either collect your cash or find out that your debt is worthless, but at least you will know.