>The government prefers W2 workers because their taxes are automatically withheld by their employer,
There is no guarantee that the tax withheld will actually be enough to cover the actual tax liability, so that is an unsupported claim.
>accidental avoidance, like when a worker fails to save money for taxes
Nothing "accidental" about it, at least not after the first year. Then it is cheating where the taxpayer hopes to take advantage of generous forgiveness or delay programs built into the system (such as Offer in Compromise) hoping to eventually run out the statute of limitations clock.
>a citizenry of 1099 workers poses a threat to government power, because the citizens can collectively choose to withhold their taxes.
Again, a completely unsupported claim. First, millions already do evade taxes and it has not yet reduced government power. The government can print and/or borrow money longer than the tax cheats can withstand it. The government can file liens against property and levy other payments to get the money from most places where the tax cheats try to hide it. The government can also require those who pay independent contractors to withhold on those payments (similar to employers), in addition of course to the mandatory reporting of such payments.
Also, those who prefer being employees (because that is almost always a better deal for the worker - for example, unemployment insurance, minimum wage, paid sick leave) would probably object to their fellow citizens, working as ICs, cheating on a massive scale.