In the case described in OP, the gambling agent was still able to find the gambler despite the gambler trying to evade the debt. If this were to be online casino, how and where will they find a gambler who they granted loan to. The money is lost for ever.
There is no room for debt in online business and that is the advantage because there is no personal relationship interphase. The casino don't give out credit only bonus for playing with them. There is no credit facility allowed but because there is physical relation in offline casino, things like that are possible.
In general, I don't think offline casinos giving their customers loan to gamble is ethical. They are just increasing the gamblers debt and risk of being addicted. That act should be prohibited.
Does this not buttress the point that the house win more than the bettor? The agents that is loaning out the money knows the gambler was going to lose again and again which was the reason to give out the money. Otherwise how would you loan money to someone who wants to "fight " against you and to win against you ? Or if you are not sure the money you loan won't come back to you as profit .