TBH it might not be a bad thing the cops seized it – Latitude is full of young teenagers and family groups; although I don’t think its “deadly” as such I believe its a very long acting stimulant and can make people quite psychotic.
Also looking at the very small amounts seized or recorded for any other drugs its either the case that Latitude has become even more of a sixth-form festival that people attend with their parents full of entire families of straightedge hipsters; or that the cops are actually being sensible and only stopping the really nasty drugs.
Probably the answer is halfway between the two.
NB: the info below is for the 2016 event, not this years. Neither the cops nor the Press have released any crime reports for this year; I don’t think anything serious did happen but the news blackout is unusual as if it really was a zero crime (or very low incident count) event surely they’d want to publicise this?