Sometimes the insurgents engage with small arms. But mostly IEDs are the best form of attack for them.
You can't blame the British. Especially not when it is well known that america poured great amounts of money into afghanistan to stop the Soviets.
Or maybe I'm wrong, please tell again how the Pakistani ISI developed stinger MANPADS to use against Soviet aircraft. I think they did do it, then sold the stingers to the us! After all, they're clearly duplicitous, cunning and evil, because how DARE those damn Pakistani general staff and ISI bastards want to have a pro Pakistani government in power in Afghanistan! WHO are they to make their own decision for their own countries when it's not what WE the americans want! DAMN THEM!
Oh and by the way, america is hemoeraging allies; american attempts to have AIM120D favoured over Meteor were rejected (after the Meteor partner nations took a slice of american money and tech... thanks for that

nice one) and The Brits insisted on (contractually agreed to) independant operation of F35 (which despite being contractually agreed to the americans tried to deny them) and are developing independant nuclear weapon targeting because it's felt that the americans simply can't be trusted. International co-operation with america is shrinking in more ways than you realise.
Oh and by the way, you may find your shares in Lockheed Martin aren't doing great because f22 is so useless it simply can't see the great and feared Taliban air force (no, really, it exists). It's well known that 5% of the people own 95% of the wealth, disputing that is a losing battle.
People are right that PMCs are making a lot of money in Afghanistan. So are the chinese, selling the latest high-tech body armour to the taliban, and 20mm anti-armour rifles capable of picking off the crew of lightly armoured vehicles even through their armour. Yet strangely nobody mentions this...
We should never have gone there, but now we're there, if we don't completely erase the Taliban we run the considerable risk of them coming back stronger and having to do the whole thing again at even greater cost.
We really need to get the populace on our side by helping them be more prosperous than they were under the Taliban; satisfied people with a full belly tend to be rather less aggressive.
As for the people who advocate taking the gloves off and demolishing/nuking the country.
Are
you
nuts?
That would provoke the whole middle-east to rise against you (you may think it has already, but it hasn't), provoke embargoes from the world, damage your economy and reputation irreversibly.
You want to advocate the use of tanks against the Taliban? That's not too great either; the best weapon is guys in boots on the ground. A tank is a big target and is rather more prone to causing collateral damage, which causes the number of insurgents to rise rather than fall.
Just ask the Israeli's; they used to use their (rather impressive) Merkava, but found that when using a Merkava to raid a village for 5 "terrorists", the next time they came to the village there would be 20 "terrorists".
Tanks could be used successfully in Afghanistan, but certainly should not be part of an assault force unless it's an assault on an isolated bunker. Better road mine patrol, check point security, perimeter defense and support fire.
So what should we have done?
We should have assasinated Al-Quaeda and funded their rivals to eliminate them. But now that;s a lot harder.
So what should we do now?
We should finish the job, boots on the ground, eliminate unfriendlies and eliminate poverty and when there's no advantage to fighting, the people will stop fighting.
Oh, and yes, The heroin trade is much stronger since we went into Afghanistan, so we are making a mint off it