That is why YC is investigating guaranteed basic income.
Also, it's already been established that Silicon Valley is not so happy with the government, so displacing an entire working class and making them dependent on the government would grant the government a power that seems against SV's interests.
Keep in mind the class distinction between someone working for the government on their own volition (police officers, military, etc), versus someone using it as a resort-- welfare recipients, SSI, veterans, etc.
The other thing to keep in mind, when you work for a company, at least in theory you hold a leverage of being able to quit and go to another job. If you're getting checks from the government (and possibly not working), you lose this leverage.