Why can the United States abandon a house when the price falls below the down payment, but we can't?

Recently, I made a suggestion: in areas where housing prices fall below the down payment, if homeowners are having particular difficulty making mortgage payments, banks could consider suspending interest payments. Once housing prices stabilize and homeowners have passed through the difficult period, they can resume paying interest, or banks could reduce some of the interest based on the house price and the homeowner's situation. This would help ease the burden on homebuyers, and on the other hand, banks wouldn't actually suffer much loss because the principal is still being repaid. Someone criticized me: Why? When housing prices rise, do banks get more money?
Don't get excited. My suggestion is based on some facts. In some places, housing prices are now falling far below the down payment. At this point, homeowners have two options: first, continue paying the mortgage; second, give the house back to the bank. For example, if U.S. home prices drop below the down payment, the homeowner simply abandons the house. They hand the house over to the bank, and the bank handles it themselves. However, in China, homeowners cannot abandon their houses.
The reason the U.S. does this is because many states in the U.S. have non-recourse mortgages. When house prices fall below the down payment, you can directly give the house to the bank. The bank will sell the house at auction; whatever it sells for, the bank gets that amount, and the loss is borne by the bank. For example, if a house has a $500,000 mortgage and is auctioned for $300,000, the bank bears the $200,000 loss.
But in China, mortgages have unlimited recourse. If you don't pay your mortgage, the bank sues you. The house is auctioned, say, for $1,000,000 on a $2,000,000 loan, and the difference of $1,000,000 is still owed. The bank can continue deducting from your salary or seize other assets to recover the debt, so the bank suffers no loss. In China, once you take on a mortgage, you bear unlimited liability. Regardless of whether house prices go up or down, the bank demands full repayment of principal and interest. Moreover, if you don't pay your mortgage in China, the bank can sue you, and your credit report will be affected, which can impact your ability to take civil service exams or do many other things.
The reason the U.S. does this is because most U.S. mortgages are securitized—bundled and sold to other institutions, earning fees for the banks and transferring risk elsewhere. In China, mortgage securitization is minimal. For banks, if the homeowner abandons the house, the loss is entirely borne by the bank. Additionally, in the U.S., defaulting on a mortgage doesn't severely impact your credit report. The U.S. also has a personal bankruptcy system.
Chinese citizens are generally very responsible; very few people default on their mortgages. Everyone continues to pay, even if housing prices drop by half. This recent adjustment in the real estate market also highlights the need for institutional reforms—how to share the losses and costs when housing prices fall. Otherwise, if someone buys a house and the price drops by 70%, leaving only 30%, but they still owe the mortgage, that is unfair to the homeowner. A risk transfer mechanism should be established to reduce the burden on homebuyers.
Without insurance or securitization mechanisms, the best approach is to suspend interest payments or reduce some of the interest. Even a two-year suspension would be acceptable. When housing prices fall below the down payment, abandoning the house incurs high costs, and without a relief mechanism, it is clearly unfair to the homebuyer.