The word “generally” in there is another of those things which makes a statement true and trivial at the same time. For one thing, it depends on how you count the fences (When you have a fence about not being a gay male and another about not being a lesbian, does that count as one or two fences?)
A more reasonable interpretation is to take “generally” as a qualifier for how wide the support is for the fence rather than for how common such fences are among the population of all fences—that is, there aren’t fences with wide support, the majority of whose supporters wish to cause harm. “Mandatory ghettoes” are indeed a counterexample to the statement when read that way.
The word “generally” in there is another of those things which makes a statement true and trivial at the same time. For one thing, it depends on how you count the fences (When you have a fence about not being a gay male and another about not being a lesbian, does that count as one or two fences?)
A more reasonable interpretation is to take “generally” as a qualifier for how wide the support is for the fence rather than for how common such fences are among the population of all fences—that is, there aren’t fences with wide support, the majority of whose supporters wish to cause harm. “Mandatory ghettoes” are indeed a counterexample to the statement when read that way.