Has anyone had an experience with the ushers while MP was in the band for example? I've seen DT more now with MM than with MP, but I don't recall any experience of being told to sit while MP was in the band. But I had issues with the ushers from the second MM US tour through the latest tour.
Again, could be the Venue seeing Dream Theater as a type of show that requires them to tell the Ushers to be more strict about obstructive viewing. Could also be, the band might know about it, but there's not much they can do, as they don't control that aspect of the bands live shows, the label could be in charge and what they say goes, and they can't say nothing, because they signed the deal.
I haven't had that problem when I went to our shows. And the camera thing could also be a label thing, or something the band decided to try. The Aristocrats at our show, had a no Video policy, you can take pictures, but if you had it up for a quite a while they'd get upset. Bryan Beller had to tell one guy to stop recording, and gave their reason why they chose to do the policy. They wanted the audience to enjoy the show, with their own eyes. I respected that decision, and laughed because our show was about 80-100 people, that's my guestimate, at a local venue that's a pretty intimate venue.
For D/T/SFAM, I was able to record and take pictures if I wanted to. I just chose not to this time. That was in Denver, and Mesa. I have actually been doing that when I would attend shows. Only taking a couple of pics, during good songs, or songs they don't really play or are good visually. If I could set up a little Tri-pod or stand, that isn't obstructing anyone's view and can still see the stage, I would definitely be doing that and recording video. I would just push record and check it in between songs, at least to make sure it's still going or hasn't died.

I wish I could share more of that Herman Li and Misha Mansoor conversation they had on Herman Li's Twitch channel. Here's just a snippet, they discussed a bit more, but I haven't seen the whole thing yet either, it's a long 3 hours. This is not 3 hours, it's 10 min...
https://youtu.be/39m3eZ7ndhs