I've taught in a diverse variety of schools and it is the support of other staff and SLT that makes or breaks it. I can think of two inner city schools of overlapping catchment in one of the country's poorest performing LAs. One was a joy to do casual supply in, not because it was easy, but because if a student wasn't going to behave in a vaguely appropriate manner, there was an effective system to back you up. The other, I vowed that I would NEVER set foot in again partly due to a student calling me a "fucking twat" without any build up... the management response was a break time detention. In every other school I've worked in, direct verbal abuse like that would get at least an internal exclusion. That level of behaviour management support leaves you with absolutely no resource to deal with routine, petty issues. My 4 days there was longer than many manage. Last a couple of weeks and the job is yours.
My worst type of student is the one that is intelligent but doesn't care about their education. The ones that know that they've got a career lined up in Daddy's business are particularly bad for this. They know where the boundaries lie and are careful about how they tip toe around them. Often naice middle class schools can be tough going, not by force of numbers, but because the staff and behaviour system can be lacking in support as they bury their heads in the sand over the few disruptive students they have.
It's never been the calibre of students that have been the issue for me, but the whole school attitude. My NQT year was tough- low level disruption was rife and when OFSTED raised it as an issue, the head snarled at the assembled staff "plan your lessons better". The real cause was an incredibly bureaucratic, long winded, ineffective behaviour management system that allowed students to drag the consequence out for about a month before it was resolved. One morning my HoD came into my room regarding a complaint that I'd asked a girl to take her coat off in my cold classroom. I pointed out that school policy was that they were not allowed to wear coats in the building and although the room was initially cold, I had survived a PPA in there for an hour before getting the benefit of a class of body heat. That kind of tedious wrangling over clear school policies is very damaging to the profession. More recently there was a saga initiated when I pointed out that a girl was wearing non-uniform trousers, and politely asked her to make it less obvious by untucking her jumper so the very non uniform zips were concealed. Apparently I was picking on her, and meetings were held analysing behaviour data etc.
Most students are lovely, but greater compliance really wouldn't go amiss. Workload has driven me out of teaching for now, not particularly the behaviour management, but much of that increased workload is down to number crunching and covering your own arse as everything comes down to the teacher's input, and none on the students themselves.
There is definitely a more entitled culture throughout the schools I've taught in compared to my own experience of school in the 90s (although I was in the nice classes of a nice school). It is all about rights with very little responsibility.