“It seems like only some of my Facebook fans see my posts. Why does Facebook do this? Is there anything we can do about it?”

Digital Marketing
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#1

It seems like only some of my Facebook fans see my posts. Why does Facebook do this? Is there anything we can do about it?

#2

Unless they’re interacting (liking, reacting to, commenting, or sharing) immediately with your content, there’s a chance Facebook’s algorithm will hide your post so no one will see it. They do this because they want you, as a public Page and presumably a business, to pay for visibility through Facebook Ads.
The news feed is continually updating to show you your friend’s posts, which means, no – you won’t see every single post from every single friend. So everyone who is your friend most likely won’t see every single one of your Facebook posts on their news feed.