Our domestic and military spending couldn't be supported by a flat tax, because to make it so a decent number of people could afford it you would have to compromise the lower and upper rates to something near 20-25%. Which is way too regressive and benefits only the top earners in the country.
Same thing with a VAT in our country, it would hurt the majority of Americans who spend 20-40% of their disposable earnings on goods and services. While providing a massive cut in taxes to the ultra wealthy who realistically only pay 5-10% of their disposable earnings on goods and services.
No to a universal basic wage, we're in lockstep there. When I say basic living, I meant just food, shelter and a single payor system which would be based off of the current employer/employee contributions and a sliding scale for others. Truly free Healthcare should only go to the disabled and those truly unable to work.
Just like the Clinton reforms in the 90s, able bodied folks should be required to be obtaining education, working or actively looking. I'd pass a major reform to needs based social security which cuts off anyone without a legitimate physical disability or an incurable mental illness like schizophrenia. Anxiety and depression wouldn't make the cut.