TLDR version: In the 90s the owners realized that if you lie about inflation you could keep COLA down and pocket the difference. 1-2% a year seems like they're just skimming the top, but do that over decades and you've stolen HALF of incomes, which we are close to reaching. Poor numeracy skills, specifically not understanding exponential growth and the Rule of 69/70/72, has allowed this long con to be run on workers.
Further reading: The BLS uses a host of 'sounds reasonable' tools to adjust inflation that were introduced or reworked in the 90s. Hedonic adjustments, OER, substitutions, outlet substitutions, and chained CPI all seem reasonable from a certain angle (which of course is the one BLS presents you), but each one breaks down when confronted with the real world, how human being experience the economy, and time. They're tools that measure utility in a vacuum, not lifestyle or ripple effect or material reality. Hedonic adjustments is an extra special lie, because it's a microcosm of the current big economic lie- "yeah, everything is worse now than a few years ago, but look how big your TV/LLM is!"
Also read up on Labor Force Participation Rate, a seemingly reasonable measure which is used to keep unemployment numbers looking better.
"Lies, damn lies, and statistics" - Twain