I think considering it’s age Nemesis for most guests is lower down the “must do” category and gets few (non-geek) re-rides and lower fast track sales. It also has a consistently decent throughput compared to other coasters on park. So lower queues. You also have to remember FV has had no real new rides for years (excluding Sub-terrible which no longer operates), so there isn’t a huge draw in FV to get guests to come along and it’s the most distant part of the park to visit. I suspect if something new opened up in that area Nemesis and Galactica would get more footfall. It’s still popular enough.