IMO, any tax system where the poorest people pay a higher proportion of their income than those richer than them is flawed.
Re: implementation: make putting money into a bank account tax deductible and pulling money out taxable, then continue to use the existing income tax system. Any money you earn that you don't spend is a tax write-off, any money you spend that you didn't earn this year is something you have to pay more taxes on.
I came up with a strange idea that is slightly better. When banks create money via loans bind the lifetime of the deposit to the lifetime of the credit. I.e. individual dollars have expiration dates that are directly tied to monthly payments. If people default then the dollars expire and the bank has to either compensate by raising its interest premium or by lowering interest rates on the deposits to compensate the loss. This means that interest rates would have to be negative sometimes and all debts can be repaid one day.
Of course the cash withdrawal scheme is equally complex because cash represents perpetual deposits which would require a perpetual government bond on the other side.
Banks would transfer their worst deposits first when you transfer to another bank which would drag all banks to roughly the same level of interest without needing a central bank to set interest rates. The equilibrium interest rate would discover itself automatically, at least that is the hope.
Of course it's probably low in importance compared to certain other modes of travel that have big externalities that aren't tolled/taxed appropriately...(air travel).
A consumption tax would be something more like "I want to buy a new hillside estate and I have to pay this special 20% fuck you tax because I'm excessively wealthy".
Consumption tax code could be fairly complex in order to minimize impact to those who are purchasing day-to-day items and other essentials. I would happily pay extra taxes on my discretionary purchases like high-end PC hardware (and probably make more of them) if it meant that on the other hand I wouldn't be penalized just for working and making money. Anything you could buy at a grocery store should probably be exempt or in a tightly-controlled tier.
Property taxes are cool too. Land is a ~fixed resource, so you have to have some counterpressure involved there. I am not saying alter property taxes to accommodate any of this, I just think they have a place.
If every road was a toll road you would have more walkable cities. Better public transport options. Less emmisssions.
Sounds like a wonderful trade off.