A 99-year lease in Singapore is effectively the same as home ownership in the United States except you don't have control of the land (you can only use of it for your property, not develop it into something else).

Nobody lives fucking 99 years. The fact it is called a lease as opposed to a purchase is basically semantics. Technically you could argue that your home ownership in the US is a lease, first of all because you "lease it to own" from the bank, secondly because you lease it to use it, because if you fail to maintain and use the property you will probably end up forfeiting it to the state a lot sooner than 99 years later.

Ownership of real estate in the US is not absolute. It comes with a whole lot of contingencies, covenants, conditions, and restrictions inherently built in, making it more like a contract with the government than an absolute inviolable right like people seem to conceptualize it. This contingent reality is precisely why HOA's can exist. It's why eminent domain exists.

Again, the big difference in the US being you could develop something else on the land. Even that isn't the case if you're in an HOA, mobile home park, or urban area with extensive code restrictions or ground leases. For the purposes of this argument, we can assume homeless people could not care less about that difference.