> solution to all these expenses is to just have the user pay the transaction costs

Then I offer an all-in price and take your customers.

The issue with bank transfers today is that the SEPA system is robust and established, but got no web compatible API.

But there are two projects (why one, if you can have two!?), one being Wero by different banks, the other being the Digital Euro by the European central bank. If either finds good adaption (Wero is rolling out slowly and for quite a bunch of banks every customer already got a Wero account automatically) this could move things around ...

> The solution to all these expenses is to just have the user pay the transaction costs.

so the ticketmaster model?

That would seem like a logical solution. So wouldn't it be convenient for the expensive payment methods if legalities prevented merchants from charging higher fees to customers using them?