TLDR: It’s probably because of your hosting provider.
I was doing a site walk-through with a client where I give them a tour of the back-end of their WordPress site as part of a client wrap-up. I started to show them where they could find the page revisions history on individual pages and I COULD NOT FIND IT. It was a live call being recorded and it was a little embarrassing. After the call ended and a couple of pages of Googling, I saw that I wasn’t crazy (at least in that regard). I couldn’t find it because it wasn’t there. Since the client hosted their website with WPEngine it was not available by default.
By default, WPEngine has Revision History Disabled.
WPEngine states…
As a managed host, WP Engine disables WordPress revisions and does not allow revisions to be enabled in the wp-config.php or php.ini.
We recommend using a separate editor to manage content prior to publishing. This protects your site and ensures positive server performance.
If you’d like revisions enabled on your website, [contact a] Support agent who can enable up to 3 revisions.
Enabling revisions is not a retroactive change and old revisions will continue to be removed automatically after 60 days.
It is possible to get page revisions option on a website hosted by WPEngine but you are limited to 3 revisions in an effort to maintain better site performance. Simply contact their support team and request that they enable it.
For more information check out WPEngine’s documentation on the matter.
https://wpengine.com/support/platform-settings/#Post_Revisions
