Plenty of magpie sized animals and smaller winged critters will face up to and confront a human threat head on and not just attack from behind. I'd therefore consider paper wasps, hornets, bees extremely brave. Yes they're only insects with tiny little brains, yes they can swarm but they do also attack solo, so in comparison, magpies are still cowards as they're intelligent enough to assess an individual and the risks they pose, pass judgement as to whether an individual is a threat or not and decide whether or not to launch an attack... with that intelligence and ability to assess a situation - maximise their offense and minimise the risk of a retaliation and decide to deliberately attack from behind - that is the very essence of what makes a coward a coward. If you punch someone from behind, it's a "coward punch".
Also, (the aggressive assertive ones) they will not discrininate, a few years back now a toddler that was no threat to the pies or their nest lost an eye in Toowoomba. Also this past season I witnessed small children aged 4-7 getting smashed by the Smithfield Park Magpies, an elderly couple in their 80's, myself, several teenagers and folks in their twenties. The aggro ones don't care, they don't discriminate. Again, plenty of magpies DO discriminate and will only swoop certain individuals they perceive as a threat while accepting food from others BUT plenty don't. My 5km daily walking/cycling commute takes me through the territories of no less than a dozen pairs of magpies and I've been taking this trek for 15 years... 3 males from 3 of those pairs will hammer me and every other passer by every time during Sept-Oct without fail, a 4th is 50/50 depending on what mood it's in and the rest just sit and watch and have never looked like swooping me. So, make of that what you will. 15 years of watching the local pies I can conclude that many do discriminate and some don't. The problem ones can and do actually get "removed" by council up here.
This is how 7/10 magpies react to me in Sept-Oct... Nothing, just watch me and the dogs walk by, non issue...
Head over to the rough side of town and through Smithfield park and all bets are off. My helmet looks like it's been shot 2 dozen times by an air rifle.
I'm an animal and bird lover, I have several of my own parrots and the ability to "whisper" completely wild birds to come and take mealworms from my hands like this spangled drongo.
I've got another photo somewhere of a heron sitting on my outstretched arm.
I'm no threat to any flying creature except mosquitoes and Indian mynas. So regardless of an individual's appearance or body language, SOME magpies are just over the top assertive and do not discriminate between any individuals whatsoever.