Airbnb have there worldwide starting prices currently set around $28 per night regardless of where you live so maybe that's what they consider as not been discriminatory.
It's a very unusual way of marketing a service that has considerable variables.
it's "comforting" to hear others who have been stung with "prompts "
alas there are Laws in every country relating to Consumer Guarantees Acts, Fair Trading Acts, Commerce Commission, Tenancy Acts, the list goes on, that are applicable and I understand that in New Zealand, as with other countries there's investigations going on
As a suggestion, if you put Airbnb into G o o g l E, & under "news" in G O oG l e you can keep abreast with what is happening where with potential and current legal & other issues relating to Airbnb.
That said, it sucks that anyone could inflict on people to not even cover basic essential cost of living costs as a result of there "prompts" to provide discounts x 2 at different percentages only to be stung with finding out that you have unwittingly given a Guest a 43% discount when you already had your property offered at the lowest possible rate to commence trade.