Then people should be free to use cash, but there's no need to lock out people who prefer card payment (I also prefer cash, but mainly because I'm old-fashioned).

But if a restaurant has a sign in the door "no card payment due to technical problems" for years, it's probably neither a technical nor a cultural/ideological issue ;)

Card payment involves fees, and buying an ePoS system, etc.

There's also the parallel EC Card system in Germany, most ePoS terminals only support normal cards, or EC card.

Its easier to just accept cash. Everyone who lives there knows cash is king, and the tourists figure it out within a short span of time.

Yeah, with "card payment" I mean EC cards of course, not necessarily credit cards :)

Card payment does involve fees but they’re not as impactful on business as it may otherwise seem. As many others have mentioned places taking only cash, especially restaurants, do so generally for tax avoidance rather than less fees from the payment processor.

As someone who does live in Germany, things changed dramatically during Covid. So many more places accept cards now and I find myself needing to withdrawal cash a lot less frequently than I did pre-Covid. There are still a ton of places that don’t take cards but a lot converted to taking cards, and some even switched to card only after seeing the lower cost of having cash (less risk of break in, less to move around, etc.)

That used to be true, but most places in Berlin nowadays accept cards. Even some "Spätis" accept them these days!

I've seen terminals "temporarily broken" for many months in Berlin.

Taxi drivers are supposedly notorious for having terminals (which are mandatory, as far as I know) that often break – and mysteriously start working again once you reveal that you do not have any cash on you as a passenger.

Taxi drivers everywhere do that to be fair.

Practically, it's just as often merchants that prefer the option of not paying tax on a given transaction.

I know quite some Germans and except very view, everyone prefers card payment.

When I'm in a restaurant looking around, everyone is paying with card (Except perhaps for very small amounts where putting in a PIN is a pain. Since COVID and pin-free payment ~<$50 this seems to have changed too E.g. paying at a coffee shop for coffee).

There are (or were) places in Berlin that accept Bitcoin.

Still are some places. The well known bitcoin bar in kreuzberg is gone, sadly. Corona killed it off pretty much. They did really good longdrinks for fair prices.