Evidence could be that Microsoft isn't in trouble for shipping Windows with RDP servers/clients in Europe, which is equivalent to this iPhone mirroring feature.

Why is Microsoft able to do it just fine (without running afoul of the DMA) while Apple supposedly can't, despite MS having an ever larger marketshare of its field than Apple and this would warrant even more scrutiny?

The multitude of third-party RDP clients (and nobody being threatened with legal action for implementing one) out there may be at least part of the answer.