What if the players are trying to make the game a way the DM doesn't want? Wouldn't you blame the players for not listening to the DM? Again, why do you think the DM's fun has to come from the enjoyment of the players? Does the DM not get to have fun of their own?
Then there's a mismatch between player and DM and something has to give. What other option is there? I can't eat Thai food because of an allergic reaction. If my friends insist on Thai, I don't join them. Maybe we go eat somewhere else or they just eat without me now and then. Maybe we all get takeout. If someone is running a game with evil PCs I'll simply tell them I'm not interested. At that point they can either change the premise or if we still want to get together it becomes a board game night.
And also, we've been talking about how the book's very easy encounter standard makes it difficult to up the difficulty without pushback from players who feel this is unfair. Any comment on that?
What comment? The DM and players should discuss how difficult they want the game to be. Some of that may well be trial and error of course, people may not understand what it really means until they experience it. But, like adults, sometimes we have to compromise because not everyone can get what they want. It shouldn't always be the DM compromising of course, it's a two way street. But it does go two ways.
To quote Monsignor Jagger, you can't always get what you want but if you try sometimes, well, you might find you get what you need. With very few exceptions ... maybe 1 in 50 players or so ... we've always been able to work something out.