I agree with that, but there is an important point missing: machinists at successful high margin employers (maybe some luxury brands) are likely to earn much more than machinists for struggling, or even dying employers. Employment is a complicated market.

The same is true for software. But there, the strongest employers are much farther ahead of their struggling peers than a manufacturer of goods could ever be. Google is putting whole industries out of business, at global scale, with a tiny number of employees compared to what they are replacing (and they probably could even shrink their workforce to a fraction of what they have today and still do roughly the same). In consequence of that it seems quite reasonable to expect that the wage difference between the wealthiest and the poorest employers will likely stay much higher than it has ever been for machinists.

Low wage programmers might find themselves in a proud "temporarily embarrassed millionaire"-trap for a very long time. (if it is a trap, "high-paying job at a low-paying company" could also be a path to zen happiness for some)