Politician A will promise "no VAT on bread" to get elected. The next guy will promise "no VAT on essentials". The next guy will promise "no UBI for the rich". And so on.
And you end up with the next politician dismantling the whole system as unfair.
But VAT is a dumb tax anyway. Anybody with high enough wealth can evade it, you just have to found a company that will pay for your computer, car and probably other stuff. I'm pretty sure I could pay for a 3d printer without paying any VAT. If I was devious, I would start a 'sailing course' company and buy my wings/sails/foil through it, while teaching once a year or so.
I'm guessing eventually we'll work out that 'fresh food' shouldn't be taxed, and the processed food should be. It's here we can work out that certain chemicals, processes, facilities, etc, are actually what should be taxed at source, and through doing so, we can save the world billions in accountancy bills.