No Mitch, I don't think it's a double standard. If I arrive there and someone is already in situ I will politely wait for them to finish or I will come back later - as I alluded. And if they are still there after an hour or two, then I will politely ask when they will be finished - and in the case I quote the photographers in question do not have any particular finishing point in mind, even when they are aware that somebody is repeatedly returning in the hope of gaining a photograph. This process can span several hours so I do not think I am being hypocritical or unreasonable! I'm talking about a busy public reserve which does not have areas specifically set aside for photographers, the viewing points are there for everyone. But I do think it's rude when a couple of big photographers with a lot of equipment park themselves and will not allow anyone else access that morning or that day. If that is their priority they should attend on a specific photographer day. That is what I do if there is something special or important that I want to photograph without being impeded. I never stay at the front of a hide or enclosure for more than a few minutes when there are other people around, because everybody deserves their slot.
A couple of years a go I went to a local reserve to see if the Tern Chicks were about, got to the hide and it was empty, no sign of any chicks, just the parents, but sat and waited, I was joined a while later by younger chap who was there with his family, his wife had gone off with the kids to allow him some time to get some pictures.
One of the adult terns flew down at the water's edge in front of us with a fish, yep chicks were in the undergrowth, took us by surprise first time so we waited for them to return.
Bearing in mind it us a fair sized hide with several viewing points, people came in looked about and left, until one woman came in at about the same time the terns returned, looked out of a different opening, couldn't see what we were taking pictures of for some reason and stated quite nastily that she would wait till we moved so she could take our places, needless to say she was ignored.
If you regularly do wildlife you will realise that patience is something you need loads of to get the pictures you want, and often come away without, it's not a matter of waiting a few minutes then wandering off, same does apllies in zoos to some extent, except the viewing areas are far more restricted so you have to expect to be blocked out.
Worst experience was a different reserve, I had been sitting quietly in a hide most of the morning watching the GC Grebes, man came in with his young daughter and insisted on sitting her on the
front of the hide to take a phone picture for his parents, she screamed the place down not wanting to do it and scared everything off, he persisted in telling her to smile. it was ear piercing so I packed
the camera away, just as a pair of swans decided to take off and leave too.
Chap commented that it would have been a good picture, I sarcastically thanked him for his daughter's help in setting it up, and walked out to a tirade of foul language