It doesn't. Inflation is an erosion of value of the currency.
General means "across the board" because the currency is worth less.
Sure, if there is a glut of apples and the price drops you may not notice the inflation baked into the price, but it's there.
And if there is a shortage of oranges the price may jump higher than inflation, but that doesn't mean inflation is higher.
People seem to be confusing general prices changes due to other factors with inflation. It's not inflation unless the currency is worth less.
If a central committee increased the price on everything without changing the monetary supply that would still be inflation. Similarly if the invisible hand does it or if there is broad collusion amongst producers.
If gas prices rise the purchasing power of my dollar remains the same for most items.
If inflation goes up, my dollar buys less of everything.
If there are several structural issues (eg greatest workforce change in 3 generations, war in Europe, worldwide pandemic, etc) they can all contribute to a general inflationary (or deflationary) trend.
It’s a very particular economic school that says only monetary policy causes inflation. And we have years and years of loose policy that didn’t put inflation on the front burner for economists to argue about.