Well, I'm sure a human domicile would be a bit more robust than "alligator Alcatraz" so instead of 8 days, it might take more like.... 8 weeks? To build something comparable for the homeless?
Depending on how complex each housing unit is (bathrooms/kitchens/whatever) possibly more or less. Idk.
But knowing that the world runs on capitalist dollars, there's no profit in it. They can't pay rent, they don't have any money, and they would actively cost you money, either in property tax, water, power, and/or food... Not to mention any replacement costs for any fixtures or furniture that's damaged/stolen.
Not saying the unhoused are thieves, but a nontrivial number of them are desperate, and desperate people do things that they otherwise wouldn't consider doing.
In any case, the solution to the homeless "problem" (being that people are homeless at all) is not just housing, but also community services to get any drug users into their respective rehabilitation programs, and anyone willing and able to work, into job placements... Mental health services...
All of these things cost money and don't yield any profits, so I understand why they're not done. That doesn't mean I'm ok with it not being done, it's a shame that we've left a portion of the population to fend for themselves on the streets and we almost universally dehumanize them as less than a person because they're homeless. They're people. We should take care of them because they're people.
No child left behind, but anyone post highschool that's living on the streets, fuck them.... I guess.