In the past quarter century, the segments of consumer prices that increased most had one glaring commonality: they were all government subsidized. By contrast, the products and services that experienced the least price inflation (or outright price declines) were those items that consumers directly purchase with their own money, transparent transactions with competing sellers and no intermediary “help.”

Each year, economist Mark J. Perry produces his “Chart of the Century,” comparing changes in consumer prices to overall inflation and average hourly wages. The chart confirms a familiar bias among free-market supporters, but is still shocking in its degree.

Since 2000, overall inflation has increased 93%, meaning that the general cost of living has nearly doubled in 25 years. Over that same period, average hourly wages increased 131%, implying that Americans have experienced a modest increase in their purchasing power. (A little less than 2% annually.)

But the category level differences are dramatic.

While overall inflation increased 93%, the cost of hospital services increased 281%. College tuition and fees rose almost 200%. Childcare and nursery school prices increased 159%. All three are massively subsidized, directly or indirectly, by taxpayers. And when the buyer of a service doesn’t bear the full cost of the thing he is purchasing, it creates perverse incentives. Buyers become less price sensitive and more willing to over-consume, while sellers face less pressure to compete on cost. When anyone other than a buyer is the funding source for a transaction, price discipline weakens.

What items increased less than the overall inflation increase of 93%? Categories where buyers pay directly and choose from competing sellers’ products. New car prices increased only 26%. Clothing prices barely increased at all. And prices within several categories actually declined, including cell phone service (down 44%) and TVs (down 98%).

The pattern held true even within categories. While medical care services increased 147% over the period, the prices of cash-pay elective surgeries like cosmetic surgery and LASIK saw for more modest increases.

Some will argue that government must subsidize the prices of goods and services that might otherwise be too expensive for people to purchase on their own. That subsidies don’t result in higher prices; higher prices require subsidies. And that technology and globalization, not incentives, explain the divergence. These forces are real, but they don’t explain why the prices of similarly complex services diverge sharply depending on who is paying.

People simply spend money more freely when it is not their own. (See almost any government entity for examples.) If you do not feel the direct impact of the price of something, you tend to use more of it. And that puts upward pressure on prices.

David Moon is president of Moon Capital Management. A version of this piece originally appeared in the USA TODAY NETWORK.