alt Hacker News> airlines charge more if you're too large to fit your seat
I don't think this is a good example, because you're literally using more of the product that's being sold. I get where you're coming from but this one doesn't seem to really reinforce the point you are trying to make. It's like selling by weight or something if you wanted to compare it to groceries.
well there are valid and invalid examples, I don't think you could have a blanket rule that covers everything
with the airline seat example some could argue that they have health reasons beyond their control and it's not their fault that airline seats are so small (they really are smaller than ever)
another example are stories of electricians charging more to people who want EV chargers installed because they already paid a premium to buy the EV, contractors will often bump up their prices if a house looks nicer, etc... these sort of biases have been rampant everywhere for a long time