What you are describing is iBan discrimination [0] and it is illegal. You can report this to authorities. Many international fintechs wrestle with this (N26, bunq) some started offering local iBans. Really annoying.
In the Netherlands we have iDeal, really nice, but only here. What do most banks not support? Instant transfer. We Dutch build our own system next to the EU one :s. It is getting better though (IE, Rabo to N26 is now finally instant).
Thanks for that tip! I was already wondering if there wouldn't be some requirement to treat all ibans equally in the European single market thing (SEPA), but didn't have time (and later forgot) to look into it.
In the Netherlands we have iDeal, really nice, but only here. What do most banks not support? Instant transfer. We Dutch build our own system next to the EU one :s. It is getting better though (IE, Rabo to N26 is now finally instant).
[0]: https://www.monito.com/en/wiki/iban-discrimination