We do set the expectations as best as we can, but the people who have these expectations really don’t like that - to some, it’s like we’re offending them, and to many others, there’s almost always some other developer they either know or heard about (they never do, in fact) that, allegedly, can do whatever we’re being asked, but 10x cheaper and 100x faster, and he’s also at a lower expertise level so we should be happy to have the job in the first place, oh and also update the documentation in 4 seconds in a way that doesn’t take away these 4 seconds from the “main work”.
Many of us love their job, or at least are very grateful to be able to have it, but we complain for the same reasons other people complain - ridiculous and/or hilarious clients, colleagues, and employers.