I think this is mandatory! You mean that btcjam does not chase the defaulter in any way? It passes it along to investors?
Correct - and most users walk away rather than go to court for what is (usually) a small amount. BTCJam doesn't care - they get their cut up front.
In Canada, it's actually very easy to collect on a debt certificate. Just simply file it in court and you get your money - the defendant has no chance to provide a defense because he/she has already lost.
I started up a website called coindebt.ca and even then I couldn't find enough interested people to make it work.
That's why you always need collateral.
Of course, by its very nature; BTCJAM is global meaning that jurisdictional and legal difference between countries makes collection of debt incredibly difficult, not to mention costly.
As said before, BTCJAM is an awesome idea but unfortunately it is a scam magnet.