> You probably can’t offer twice the strength and speed of an average worker (definitely not 10x)

You couldn't be more wrong. First some numbers just for laughs:

Greatest weight lifted was 6270 lbs or 2844 kg while the safe limit for average men is 55 lbs or 25 kg.

Greatest speed was 43.99 km/h (27.33 mph) while average men do 10 km/h.

Then there is endurance too of course! Forget about strength and speed, 8 hours is a huuuuuge amount of time for any physical effort. Walking one could theoretically do 25 miles or 40 km in 8 hours but nurses walk only 4-5 and that is considered a lot. I'm not aware of any 8 hour races but Aleksandr Sorokin did 308 km in 24 hours which is 3 x 8 hours.

You probably wonder why I compare it to top sports. That is because in my humble opinion it is. If you don't treat physical labor like top sports, if you don't make an effort to adapt all parts of your lifestyle to it, then it you will destroy your body which will bring down productivity dramatically. The average worker is pretty used up.

In many such jobs not going insane also takes a huge effort. Its not as black and white as it seems. Most of us are partially nuts and make a constant effort to preserve sanity. Long before one jumps down the foxcon stairwell the insanity starts eating you.

If we didn't need them we wouldn't have weekends. You would just hire someone willing to work 7 days? Take it or leave it? 15 hour shifts anyone?

Who is the average worker anyway? Are we grouping 20 year olds with 60 year olds here? Your average 60 year old manual laborer (besides the insanity) has a laundry list of permanent injuries that prevent him from doing cardio. The have (besides experience) a high pain tolerance to work with.

Then there is quality. Focus isn't exactly equally divided among men.

Motivation. Besides from ability one can often chose to do less work or chose to do more. The difference between wanting to dot all the i's and waiting for the big bell to ring is huge.

People are also extremely different in how they think about tools and methods. For some they just are, for others they are a half baked work in progress. Everything can potentially be improved. What better time to think about it than during usage? The more mindless the grind the greater the opportunity. You don't have to be a genius, you get 40 hours per week to think about it.

Communication and social skills! I'm pretty good at this if everyone has his eyes on the ball. If everyone else is just waiting for the bell to ring I'm toxic, useless and I hate life. I want to marvel at my accomplishments regardless what the job is.

Ill do one funny story that can only be told in full: While wiring houses I got to see many companies build walls and ceilings. One day a team of 4 showed up that came in running with the largest size plasterboard that one can buy. They carried it inside slapped the first one onto the ceiling in less than 1 minute then ran off to get the second one. The secret of the formula was that the boss was 6.9 and the 3 employees were all over 7 feet tall.

The same day I worked on a different project where 6 old short carpenters with a thousand years of experience between them spend the better part of a week filling up a floor with scaffolding to do exactly the same job. (It was a pain moving my materials and equipment around.) They [had to] use small more manageable plasterboard which requires a lot more wood framing, a lot of sawing and a lot more screws. It took them 4 more days to put in the plasterboard, after that it was the usual patch work of seams that has to be plastered to be presentable.

I didn't see them put in the framing but it was simple by comparison. In 20 min the fast team covered a giant living room. It was surreal to look at. 4 pushed the plate against the ceiling, the 5th guy measured and cut it while they yell at him to work faster. Afterwards they spend 10 min laughing. I ask the entrepreneur among them how he found those giants. In the pub he said, I look over all the heads and point at the tall guy then yell, you should come work for me! What is the work? Well, we drive a lot!

I didn't see them do the wood frame but I wouldn't be surprised if it took them 1 hour. Lets say 2 hours for the whole job: 6 men 8 days vs 4 men 2 hours = 48 days vs 1 day. Almost 50 times more productive.