By definition? Whose definition? The people issuing the currency?
CPI is an extraordinarily misleading measure of inflation, and the problem is built into its design.
Redefine inflation from the expansion of money and credit into the changing price of a selected basket of goods, then pretend you've measured the destruction of purchasing power.
Here's the absurdity: In the UK, beef prices have risen 60% over the last decade, compared with just 27% for poultry.
Imagine a family that used to eat steak regularly. As beef becomes increasingly unaffordable, they switch to chicken. Eventually even that becomes a luxury, so they start filling their plates with cheap starches and ultra-processed industrial sludge.
Of course people substitute cheaper goods when they can no longer afford what they used to buy. What choice do they have, starve? And here's the beautiful trick: CPI weights are periodically adjusted to reflect what people actually spend their money on.
The very inflation that forces people to downgrade their consumption influences the basket subsequently used to measure inflation.
It gets worse. UK CPI excludes the cost of purchasing a home. But even more absurd is that none of this captures the prosperity we should have gained from decades of technological progress and increasing productivity.
That's what makes CPI such a wonderfully convenient political instrument. Expand the money supply, watch people gradually settle for less, update the basket to reflect their new spending habits, and then point to the index as proof that inflation is under control.
The population gets progressively poorer in what it can afford, while the official statistics remain respectable.
1/CPI is real inflation by definition. It's the increase in the price of a basket of goods spent by the average person in the UK.
A non-skilled worker is not an average person. Their spending is different from the average and their inflation is wildly different.