My party wants me to railroad them?

I'm two years into a campaign, gone from level 1 to 10 so far. I've worked hard to work in plot threads that relate to each character in addition to the overarching story. The problem is, even though my players <em>say</em> they want this, they have never once followed up on any of those plot threads. Instead, they only follow the main story - but only because they have a quest giver, and they only do the quests he gives rather than pursuing anything else that might interest them.

I've tried making things more open-ended, but when they have a list of four things to look into and I ask them what they want to do next, they just look at me and shrug and wait for me to tell them what to do. This is bad enough that when we had a "beach" episode (a night off at the inn), one of the players refused the little fun things I dangled and instead had their NPC sit in a corner drinking all night - while still expecting me to somehow entertain them.

It's starting to feel like they just want me to put on a radio play where they roll dice sometimes. Does anyone have any advice on how to engage them a little more? Should I... create a spreadsheet with possible plot hooks and have them throw darts at it? I want to play a <em>collaborative</em> storytelling game, not sit there doing all the work while they just kind of passively absorb it and then tell me how much fun they're having.

To head off the "talk to them about it" suggestion, I've tried a couple of more gentle approaches where I tell them they need to take more responsibility for what their characters do, but then they spent 70 minutes anxiously looking at each other and agonizing about what to do before asking me to just tell them.