I've known people who have piled up debts that they cannot pay. Being hounded by debt collectors (and avoiding them) just becomes a way of life. Re-possessing assets? I am assuming you mean the asset that was purchased with the credit that resulted in the debt. This wouldn't have to change under the proposed system. There would still be secured loans.
Garnishment and levies? In practice these are pretty rare and costly for the kinds of debt here. You see this more for taxes and child support, not unsecured consumer debt.
Instead, credit dings (chargeoffs, etc.) are the most common result, and that wouldn't have to change under the proposed system. So, there's your deterrent. Those "deadbeats" you mentioned would then not be able to obtain credit. In fact, credit requirements may become more stringent if lenders really perceive risk from "deadbeats" under the new system.
>...the "I want it now and I will pay for it later" attitude.
If anyone needs deterrent, it's the reckless lenders. Marketing works and for years, the mesage from creditors and retail outlets has been "you can have it now and pay later". In fact, some "retail" outfits were nothing but credit providers using (often cheap) products as a vehicle to sell credit. Think Rooms To Go.
And some people are just not as sophisticated as others. So, when selling easy credit in abundance, you are more likely to attract and empower those who are least able to afford it. OTOH, we have an entire industry set up to determine creditworthiness and businesses that sell credit are far more sophisticated than the average consumer, yet somehow it's the consumer who gets in over his head who is the morally bankrupt deadbeat. The creditor is merely a victim, though they still manage to make a profit. And, oh yeah, if the largest of these do get into trouble, because the outsized risk they took for outsized profits finally backfired, then we bail them out and restore their saintly CEOs' compensation to its rightful place in the stratosphere.
On balance, the current system smells an awful lot like a racket.