Amsterdam and Prague are two examples of large airports in Europe, where non-Schengen departures involve security screening at the gates. This is mainly to make non-Schengen transfers as easy as possible.
And because each of the non-Schengen destinations and airlines seem to have their own rules for security screening... I recall a transfer in London where I met two security checks, The standard UK one and then a gate check for boarding an airline from the USA. Add that to the security check I already went through in Amsterdam...
