EDIT: I apparently fell for a fake news Lemmy community. Its explained in the sidebar. I gave the OP the benefit of the doubt that they couldn't link the real new story, but trusted the attribution to APNEWS. If you enjoy participating in OPs social experiment on posters you're in the right place. I'm not, so I'm out.

I don’t know if it is tax evasion (I am not a US tax expert), as it would be up to the receiver of the Robux to declare it as income and pay tax? Correct me if I am wrong there, but from a cursory google, you can be taxed on all kinds of income, including bartering, so it should be possible to pay taxes on it.

You're mostly right, but missing a few key pieces of US tax law. Roblox can hire the developers you're referring to either as W-2 employees, which would require Roblox to withold taxes (and pay into our nation pension system called Social Security). The other way is to hire the developers as "independent contractors", but this means Roblox would be required to hire them as 1099, which means they Roblox doesn't have to withhold taxes, but does have to report the money they're paying to the contractor. The contractor would then be obligated to pay the taxes on all earnings themselves.

If Roblox is neither 1099'ing these devs nor W-2'ing them, yet Roblox is employing them and paying them, then Roblox would be in violation of US tax law, and the IRS (Internal Revenue System) which handles individual and corporate taxation in the USA, would come in with enforcement resulting in potentially heavy fines and additional audit requirements to Roblox for years to come.

I would at least be completely honest with the person, and tell them that the choice is either be homeless or effectively owned by Walmart. But I don’t think its correct to frame this as a binary choice, there are other options. Homeless shelters do exist,

I would be surprised if a homeless person would not be aware of homeless shelters. If you look into homelessness, you'll find there are some very real concerns with shelters and some elect to not use them. Others are simply at capacity and more homeless remain unhoused.

even if there aren’t enough, and Walmart could donate these cubes to a shelter organization to operate them independently.

That assumes Walmart is trying so solve homelessness. Walmart isn't. Walmart is looking to increase its staffing pool. A reduction in homelessness is unintended side effect.