I dont consider things you described at daycare talking back. To me its more like a whine.
Telling an adult to eff...totally unacceptable.
I saw some of the kids where we lived being disrepectful of adults (mainly Sunny and another boy who eventually moved out). I thought those two were the exceptions. Then to hear dd tell me some of her classmates talk back to the teacher, I was shocked.
A little t/j but kid related...I learned a new way of saying I dont want to go home: "Im not expected home for two hours". (kid was sent home bc my kids misbehaved and did something that could have caused the three of them harm). A good one, lol.