You answered your own question, one of the ways is to "adjust for consumer preferences" the goods baskets You can also change the weights for various localities or overstate how much better the new version of a product is and reduce its weight.
Fundamentally the BLS in the US has no incentive to accurately report inflation. They are a department of the executive with no real safeguards against political influence. Reducing the official CPI reduces the government's expenditure and understating inflation is a great way to do so without officially cutting any budget item.
Further, see my sister comment to yours, inflation is personal, a country-wide single-number inflation measure is broken by design.
Fundamentally the BLS in the US has no incentive to accurately report inflation. They are a department of the executive with no real safeguards against political influence. Reducing the official CPI reduces the government's expenditure and understating inflation is a great way to do so without officially cutting any budget item.
Further, see my sister comment to yours, inflation is personal, a country-wide single-number inflation measure is broken by design.