Where the hell are the boys' parents 95% of the time? Somebody seems to be ensuring that they get to school each day (as they don't seem to be the sort of meatheads to do that on their own) but other than that they seem to run roughshod across the rest of the neighborhood. Is there anybody who cares enough about these two yahoos to ensure that they don't kill themselves out of boredom and stupidity?
They probably only go to school because they have to show up to get lunch.
Better yet, who pays for their utilities, cable, and electricity?
This Troper once worked at a McDonald's and it had like 8 employees and apparently Burger World only has 3 employees which are Beavis, Butt-Head, and the unnamed manager... HOW DOES THIS WORK?!? Apparently the manager doesn't even think about hiring more employees and that can explain why the lines are long due to the incompetence of a certain two employees, plus when Beavis and Butt-Head aren't even working, who is working at Burger World in their place? This doesn't seem to make sense at all! Unless the Unnamed manager is as inept as those two but doesn't admit it.
There are probably more, but they just aren't seen, since they wanted to conserve the number of characters seen at a time, or didn't want to create all-new ones.