I've always wondered, why can't we just pay one tax? Say make income tax 1.5x what it's now and cancel all other taxes. That way it'll be even easier!
Example: I route my investment earning via a company, that company can claim expenses such as paying my utility bills and buying my groceries, anything leftover they give me. They work it out so my net income is zero, oops.
It's easier actually to tax purchases.