It's proven that disguising the tax convinces the ignorant consumer the product is cheaper than it really is. So stores don't include taxes on the price tag, and lobbyists work hard to prevent it being legislated.
That is the only reason. It's not transparency, this is the exact opposite.
Focusing on money supply misses the most significant factor in inflation, missed by all armchair economists- the private banking system.
A $1 million asset is not part of the money supply, if it's value increases to $2 million it has no impact on inflation.
If the owner of that asset then aquires a loan against that asset and spends that money, they have increased the money in circulation. That is a far more significant driver of inflation than government spending. Meanwhile the FED (or equivalent) has not printed one additional dollar.
These models don't work because they ignore the MOST significant driver of inflation