Earlier quoted context omitted.
Windows is extremely well sunk into the enterprise market, and neither Linux nor Mac are at all focusing sufficiently on it to displace them. Linux isn't user friendly enough, and Mac's support policy is a complete no go for enterprise.
Every enterprise I have worked at had both linux and mac available to developers. Is this not your experience? You seem to present as truth the opposite of what I have lived.
Macs are usually only available to upper management, unless required for iOS development, in which case they are part of a pool shared among project teams.