Prices don't go down, they only ever go up.
There is no situation in which interchange fees get slashed and prices go down across the board by 3% to make it worth it for card users.
> Prices don't go down, they only ever go up.
Well, there was that time in the 1930s.
Prices do, in fact, go down. For example, eggs in the USA went down from $6 to $2 in the past few months. https://www.macrotrends.net/3052/us-egg-prices
Long term average? Sure, it goes up, that's inflation. But do you know what causes inflationary pressure? Visa and MasterCard adding unjustified fees because they're a duopoly and control most of the payments market, and your government won't regulate them and cap fees.
The UK and the EU both cap debit card fees at 0.2% and credit card fees at 0.3%. When the UK left the EU, Visa and Mastercard jacked up their fees over 5x for UK-EEA payments. Not because they had to, but because they could, and they love sucking money out of other peoples' businesses. https://www.psr.org.uk/our-work/market-reviews/market-review...
Retailers in competitive industries absolutely do use a reduction in card fees to lower their prices. Maybe not all the way, but they definitely don't give it all to themselves as margin; their competitors don't.