Gosh, why indeed? It's a puzzle, isn't it? Allow me to refresh your memory a little:
The simple answer is: "Because you let them think they could get away with it..."
It's called 'consequences'. Of weak, vitruesignalling 'leadership'. Of cowering before a mob.
The Metropolitan Police Federation, which represents rank-and-file officers, said attacks on officers seem to be increasing, adding: 'Yet again this starkly shows the dangers @metpoliceuk face and the bravery they show each and every day keeping Londoners safe.'Not all of them showed 'bravery'. I wonder if seeing their colleagues kicked to the ground gave them a twinge of guilt?
There's predictable condemnation from all those who previously sowed the wind, but will never find themselves on the streets to reap the whirlwind. But one man gets it:
Shaun Bailey, the Conservative candidate for next year's London Mayoral elections, linked the incident to the Black Lives Matter protests, which saw police criticised for failing to take a tougher line with demonstrators. 'This is what happens when you try to appease the mob,' he tweeted. 'You lose control of the streets.'Maybe the Police Federation needs to look a bit closer to home?