The EU objected to Microsoft having access to APIs that third party developers did not. There has been no EU objection to creating new security APIs that would

The EU objected to Microsoft having access to APIs that third party developers did not. There has been no EU objection to creating new security APIs that would be accessable to Microsoft and third party developers. As far as MacOS goes, you can't infect the system files with malware when the whole partition they live on cannot be modified by anything but the OS, which does indeed seem like a valid technical reason.