> I don't see any tunnels on high mountain expeds?
Oh yes, I know, so let's look at why and what this means for you.
Expeditions in the Himalayas etc usually have lots of people and lots of porters. You have only to look at a typical scene at Everest Base Camp. This has several consequences:
* Weight does not matter: porters are cheap
* Expeditioners like big tents so they can all sit together playing cards (or whatever)
* The expedition doesn't want to spend a fortune on expensive tents
Big heavy geodesics satisfy these criteria. But many of the tents you see on expeditions are 3 and 4 man geods. They don't have to be all that sleek: move up to 70+ d nylon and 10 mm poles and they will take an awful lot of abuse. Hey - there's even a bakery at EBC!
The TNF 2-man Mountain 25 is ~$500 but weighs nearly 4 kg
The 2-man Qasar is 450 UK pounds but weighs over 4.3 kg
The 2-man Trango 2 is ~US$525 but weighs over 4.1 kg
The 2-man Macpac Olympus is 3.1 kg but it's NZ$900 bought in New Zealand: a bit more when bought overseas. That's a lot more dollars.
The double-skin geods usually require you to pitch the inner tent first and then to throw the fly over it. That's OK in fine weather, and who cares at 7,000 m in a snow storm anyhow? But try pitching one in seriously wet weather: the inner tent will fill up with water while you are securing it. Pity about that! And since the guy ropes are attached to the fly while the rather long poles are attached to the inner, embarrassing things can (and do) happen in a gale.
The single skin geods pitch more easily, but very few have good ventilation so they do collect condensation. And rarely do they even have a vestibule. Hard to get in and out in the rain.
Have a wander around YouTube. There are quite a few amusing videos of people trying to pitch a geod in a strong wind. They have a lot of trouble trying to hold the inner tent up without snapping poles while someone else tries to secure the (wildly flapping) fly over the top.
A tunnel tent has short hoop poles, and shorter poles are stronger. A good tunnel tent is pitched fly-first; the better ones have 'integral pitching' - both inner and outer at once. Rain does not get in because the fly is always there. A good tunnel tent has the poles attached to the fly, which makes it significantly more storm-proof. It is quite easy for one man to pitch a tunnel in a howling storm without risk. (How do I know? ... ) And they have good vestibules.
So why are there so many geods and domes on the market in America? Dunno - I suspect cheap free-standing pop-ups started the fashion and the geods were a natural progression. But go to somewhere like Northern Europe where they know about bad weather, and you find the Hillebergs and similar with their tunnels.
Of course, our neighbours the Kiwis (New Zealanders) will simply smile at all this, because they have their own little weather system down there. The Maori name for NZ is 'the land of the long white cloud'; visitors sometimes translate that as 'the land of the long black never-disappearing cloud'. Some places in Australia have similar weather: the Main Range during winter for instance. 100 kph winds (with white stuff) are quite common in both countries, but the weather can get worse...
A final thought. What happens to a geod when it loses all its guy ropes? Embarrassing - a lot of flex. What happens to a tunnel when it loses all its guy ropes? Not much if the wind is any where near end-on. Yes, field tested ... :-)
Sooo... what an expedition buys for the porters to carry, and what an individual should buy to carry himself, can be a bit different. What should YOU buy? That's up to you of course (and your budget!).
I was just challenging the apparent assumption that only geods can be bomb-proof.