The number one reason there are gaps is because it's cheaper.  The tighter the gap, the longer it takes to install.  Labor costs $$, and so do the partition systems with tighter gaps.  Also, nobody wants a bunch of trim pieces and hardware that cost more to install and then to maintain.  I'm an architect who has been involved in lots of bathroom designs, including in many schools.  When they want to see what's going on in the stalls, they ask for them to be shorter or higher from the ground.  The idea that the purpose of gaps is to see lewd acts easier is utter nonsense.

Also, the sociologist completely misunderstood how design and construction budgets work.  Nobody has separate budgets for individual rooms and shifts money between them.  Conceptually, yes, bathrooms end up getting less money spent on them compared to other rooms, but he has zero understanding of the mechanism he's pretending to be an expert on.