Disney has tried to hide lines and give separations, I know a FOP that is one before you get fully inside the building but you're in the cave system and you can still see the outside, but you know when you're stopped for a long time you can peek over the tall barrier and see it's because it's the merge point otherwise you don't have any idea why you're just stopped there. Over at Universal you have EP lines that are right up along the regular lines but you don't really have as many merge points, many have their own dedicated loading area as well.
There's a portion for example on MIB right that EP users go to a separate area to scan again their EP pass but by in far they are right up along it. Because there's not so much stoppage for merging the Standby users, Single Riders and EP users are kept in their own line for pretty much the whole way. Now Seuss High in the Sky is separated at the actual loading where you're on opposite stairs but the lines are up against each other for a decent portion of it.
That's not to say there isn't angst at Universal with EP users but it seems to be less vocal, less turmoil even though the lines are right there. It's kinda like being in traffic and you're more frustrated because you can't see what's going on up ahead, you want to know why cars are backed up but there's a SUV or a semi in your way and if only you could see you would at least know what's going on. When you're in that Standby line at Disney and you're trying to figure out why you haven't moved in 10 mins it can make you even more upset.
Ultimately, at least IMO, yes people are paying for a service and someone who is not paying for it can easily get annoyed at that mere fact but if you're waiting a measurable amount of time more, some of our waits in 2022 were doubled what the initial standby wait was when we entered the line just because a slew of LL users came through, and then you're having to wait even longer than anticipated it all builds up. So just adjusting how these lines see each other or their physical proximity to each other doesn't work to solve when your wait becomes longer and longer because Disney is waving on LL users in such high amounts. But there's not as much incentive for Disney to do this especially now that they have a watered down EP but priced higher on average LLPP.