This is also a bit of what I will call reactionary posting, meaning people will respond to something presented to them, rather than taking a bit of a lead.

Eg: you see some keys on a desk that are for a nearby door. The other player then also notices the keys. You them take the keys and open the door, entering the room. The other player follows.

I can go on for a bit longer, but these sort of follower players are hard to manage because they never really do much other than appear in the RP and the story doesn't generate around them because they aren't really getting involved.