which changes all the time with regular price fluctations/discounts/etc

I have noticed e.g. with toilet roll when they decrease the weight they bundle it with a temporary discount so that the unit price remains the same (or even decreases for a bit)

then once the discount ends you've forgotten that they decreased the weight

it's a random walk, with the shrinkflation causing it to go upwards over time

it's the same trick e.g. Google does with Google Workspace, when they want to increase the price they:

  - increase regular price, but introduce a new permanent "12 month plan" with the previous price
  - six months down the line the 12 month plan is discontinued

then they repeat next time they want to increase the price