There is a fair bit of passing in the middle of the pack.
The problem with F1 is that the engineers and drivers are exceptionally skilled. The engineers are always finding ways to make the cars go faster until the FIA (governing body of F1) puts in new regulations to slow them down. They are also always introducing new concepts and rules to try and promote overtaking (passing, as you'd call it) but the drivers are always finding ways to adapt and limit overtaking opportunities.
The truth is that the gap in speed between the cars in every tier (if you think of it as high/mid/low tier cars) is pretty minimal, so you can't blow by guys on sheer speed. The end result is that you have to enter a turn faster, exit a turn faster, or take an alternate racing line in a turn to try and make the pass. Each track only has a few strong turns for overtaking, and there isn't a lot of track space for you to try and squeeze yourself on the inside of a turn or for you to try and go wide.
Most of the drivers in F1 are excellent at defending their racing line and boxing out an opponent. Every defensive maneuver throws the trailing car back some time because they have to slow down a little bit to avoid a collision.
I feel like the F1 vs NASCAR "debate" has some parallels to the defensive vs offensive style hockey "debate" in the NHL. F1 doesn't have a lot of passing, but it is a showcase of very skilled driving. NASCAR doesn't have that same kind of skill on display, but it does have a lot more action. The F1 fan is like the guy who would rather watch a 2-1 hockey game with two teams playing strong defensive systems, while the NASCAR fan is like the guy who would rather watch a 10-9 hockey game with a lot of run-and-gun offense with sloppy defensive/positional play.
To each their own. I have a hard time watching full races period, but I much prefer F1. I'll usually watch the races for my favourite circuits (maybe five out of the season) and that's it. The rest is just highlights. Ten minutes of NASCAR puts me to sleep.
The bolded part shows you don't know what you are talking about. And it's not your fault; it's just the common perception. For a full rebuttal, look at my posts on the previous page.
If NASCAR required no skills at all, you'd see every former open-wheel drivers (and we're talking F1 champions here like Jacques Villeneuve) succeed in NASCAR. Is that the case? Far, very far from it.
NASCAR requires different skill sets. Racing in a close pack, bump drafting, mastering those 4,000lbs/no-frills car is much different than driving a state-of-the-art 640kg F1.