You object that capitalism works too well, that more efficient means of production drive out less efficient, leaving everyone with sterile and repetitive jobs in a soul-killing environment.
More efficient means of production do drive out less efficient means, but your definition of efficiency is too narrow. If under one arrangement a worker produces a dollar an hour more than under another, but the conditions are so much worse that he will gladly accept a wage of two dollars an hour less to work under the other, which is more efficient? For both the employer, who saves more on wages than he loses on production, and for the worker, the 'less productive' arrangement is the more efficient. The efficiency of capitalism takes account of nonmonetary as well as monetary costs and products.
Let's suppose that I build radios on an assembly line. Rather than having a single task on an assembly line, say driving 6 screws to secure a cover, I'd prefer to install the circuit boards, the display, the heat sink, the covers. Everything. Because it's less boring and improves my skills.
That will reduce output. But you can have that in Capitalism, says David Friedman, because if you are willing to accept lower wages profits can be sustained even with the reduced output.
But there's an important question Friedman hasn't asked. How much less in wages are required? Maybe I'd be willing to take a 20% reduction in wages for a 20% reduction in output. What if I had to take a 90% pay cut for a 20% reduction in output? What if the former is the case on Socialism and the later is the case on Capitalism? Then guess what? The Socialist criticism is spot on and Friedman has not rebutted it.
Take a look at Foxconn, which makes your ipad and iphone. Workers make about $17/day working 12 hour shifts. When wages are already a tiny portion of overall expenses it may not matter how much less you are willing to earn with wage labor. You could go from $17 to $0 and still see profits reduce.
Below I offer a hypothetical example under Capitalism. Investors want profits. They'll be happy to alter the work environment as long profits are sustained. So let's suppose we have 100 empolyees and they produce $500 in value each day. Let's assume their total compensation is $90/day. I have an assumed capital expense as well. Under those conditions you see $31K in profit per day. Click to enlarge.

To the right I have the same conditions except the work environment has been altered so the work is more interesting and total output decreases 20%. I assume a 10% reduction in capital expense because fewer material is used. Based on this I calculate the required wage rate in order to sustaine the $31K in profits. The wages must fall to zero. Also if the initial wage was lower than $90 paying $0 would not be low enough wages to sustain the $31K in profit. Capitalism does not permit a less monotonous reduced output work environment under these conditions.
Contrast with Socialism. I have the same initial conditions, but on Socialism there are no investors that are paid. The workers only are paid. Worker wages start much higher since the bulk of the money is not going to the investors. But to permit a 20% reduction in output in order to improve working conditions workers must be prepared to accept 22.5% less in income. Much more than they make even under monotonous Capitalist conditions, but still a sacrifice.

What you find if you increase the initial wage rate on Capitalism is that you don't necessarily have to go all the way down to $0 to sustain the payments to investors. But you still must accept a greater % reduction in wages on Capitalism than you would on Socialism.

