Yes but people expect to get their digital goods immediately, not in 1-2 business days. SEPA Instant support is spotty and even if it wasn't, I don't think that the tooling around SEPA on the merchant side of things is built to handle transaction in real time the way people are used to with cards.
Supporting instant payments is now mandatory in the EU on the receiving side, and in a couple of weeks on the sending side. No surcharge allowed either, which usually means it's free.
Arent those instant nowadays ? Also if there was a reason those take some time or are not as convenient as car payment so far (not sure there are any such reasons) you could just fill your Steam wallet and then pay for individual games from that.
Even if the payment is instant, the processing on merchant's side typically isn't. If I place the order at 5 in the morning and pay with card, it's ~always shipped the same day. Conversely I've never had the order processed the same day when paying with SEPA.
I don't know where the bottleneck is, but I've personally never shopped anywhere that was set up to process SEPA payments rapidly.
