You should use cash. (a progressive case for cash acceptance)This post exists to do two things - explain to small business owners/operators why they should accept cash, and to individuals why they should prefer using cash. Some points are shared between the two. There's plenty of folks out there who will argue for cash from conspiratorial or right-wing perspectives, and this post is gonna steer clear of conspiracy theories and argue for cash from a broadly progressive perspective. OK, let's get to the point.
Not accepting cash is discriminatory against marginalized people
Maybe that's a strong sounding point to start off with, but by not accepting cash you are directly preventing a lot of the most vulnerable people in society from being able to buy your stuff. Marginalized people often end up preferring, or requiring cash payment, for a bunch of different reasons, including:
Older folks and disabled people who struggle with using a card terminal
anybody who does not have a bank account (be it because they are a recent migrant and there is a language barrier to opening one, they are homeless and they can't apply for one as they have no fixed address, a child, somebody who can't get government ID so they can't open a bank account, etc)
those who rely on welfare (often due to disabilities) and have their bank accounts monitored by the government for "anti-fraud" purposes
financial abuse victims who rely on cash as their bank accounts are controlled by a malicious party
This is not nearly all the reasons somebody may prefer, or require, cash payment, and by only accepting card you are discriminating against those people's ability to choose to support your business. As a business, it loses you customers, and should probably give you pause for ethical reasons too.
Card providers are not a neutral party
Card payment processors, like Mastercard and Visa, are not neutral, benevolent bodies that just want to make payment easier. They're companies, run for profit, and by people with ideological positions. They take cuts of transactions and charge fees, meaning that (as a business) you get less of your customer's money and (as a customer) you face higher prices as a result. Mastercard, in particular, has been known to throw its weight around to try and affect political change (such as by blocking donations to wikileaks) as well as using their ability to block people's ability to receive payment to police online adult content, take down people's work from distribution platforms, and generally screw over creators of adult content even though what they are doing is entirely legal, and necessary for their work. (and before you call this frivolous because it's about porn - adult creators are people doing work, and a lot of these changes have severely limited their ability to make a living)
The major card providers in the western world - Mastercard, Visa, Amex, Discover, etc - are all based in the US and receptive to US regulations and pressure, which may also concern you for political reasons that it is beyond the scope of this post to go into.
Cash protects your privacy
Mastercard denies they sell transaction data. Even if we take them at their word on that (and there is reason to be suspicious) it remains the case that every transaction you make with a card is logged, either by your bank, or by the credit card company. Even if your transactions were usually private, there's still plenty of times where you get asked to hand over bank and card statements, especially if you are lower income, dependent on welfare, etc. Anti-fraud and affordability checks on renting, buying property, credit scoring, or any interaction with the financial system in general often requires handing over transaction histories.
From our experience, especially with welfare in the UK, we have been asked to hand over bank statements, card statements, and even crypto wallet transaction histories under threat of losing access to welfare if we don't. The obvious solution here to retain any privacy and dignity is to conduct payments using the only method that doesn't have any logs - cash.
What you should do about this
If you are a small business owner, you should accept cash. Unlike taking card, it's free, nobody takes a cut of anything, and the most new equipment you'll need is a cash drawer.
If you are an individual, you should use cash when possible, and if you really care about this, you should boycott places that do not take cash. Name and shame them online, add to their openstreetmap entries that they do not accept cash, talk to your local politicians about pushing forward motions to require businesses to take cash. Promote cash acceptance and vote with your feet and wallets. We're not ones to usually endorse such approaches, and are not trying to argue that businesses not accepting cash is the most important problem in society right now, but it's still a problem, and one that can be solved with legislation. Many countries already compel businesses to accept cash, so there's strong precedent.