OK, sometimes there are reasons beyond your control for late arrival at the check-in (traffic jams, rail delays etc).
But why do so many people actually plan to arrive at the last minute?
The only thing one can admire Ryanair for is sticking rigidily to their check-in time. Except when the queue is of their own making due to inadequate staffing.
Airports aren't much fun these days, with the constant security paranoia. But I hate being rushed, so invariably plan to arrive at the car park a minimum of 1 hour before the 'last check-in time'. More if the journey to the airport is during a rush hour. For London Airport and its far-flung long term car park and tortuous internal road system, add at least another 30 minutes....
Pedantic and jobsworth British way of life? Not really. It's just the idle travellers who think that the world revolves around them and who think it's OK to swan up to check-in 10 minutes before take-off who are wholly to blame.
Last check-in 0930 does not mean 0931...0932...or 0938. Why should it?