You sure about that? This is straight from the Gmail App...
View attachment 82788
Non-Nexus devices (most if not all of them) don't come with the Google exchange package on the device, and Gmail won't see the OEM-specific Exchange client software on the device in most if not all cases. You can hack the Google packages in if you get them from APKMirror or somewhere, but they don't ship on Samsung, HTC, etc. devices by default.
OEMs are responsible for licensing Exchange themselves for use in their Android devices - because each device has to be licensed and I don't think Google wants to pay the license fees for the entirety of the Android device ecosystem themselves. That's why they dropped Exchange from consumer Gmail to begin with. It gets very expensive.
In any case, Gmail is a poor Exchange email client and Samsung/HTC have far better PIM clients and Exchange Email clients on their devices than Gmail and Google Calendar, among other things.