Productivity is why US software developers can earn so much. Not because they're so much more productive in lines of code versus the rest of the world. Rather, because software developers at US tech companies produce very large economic outcomes on average.
So do software developers in many other parts of the world. The difference is more that employment is a competitive market and the market rate for a decent software developer in the US tech hubs is recognised as being much higher than most other places so people moving jobs expect higher rates. Sadly, those rates do not necessarily need to be tied to productivity in any meaningful way, and so in much of the world software developers continue to be paid far less than the value they can generate because they don't negotiate well or bargain collectively to push salaries up.
However, it's not really a fair comparison. For example, in the UK, a lot of us solve that problem by going independent at some stage. At that point, you are dealing with clients on a business-to-business basis where fees charged can be related to value generated, and if you know what you're doing and get results, you can far exceed the income that almost any salaried software development position will offer.
Similarly, there are a lot of small tech firms here that are not SV-style startups with big funding and aiming to be the next unicorn or to fail within a relatively short period. They're just a few people who've got together to take on bigger projects or invest in more infrastructure or otherwise scale up, and they're happy to be doing that indefinitely and again making better money and enjoying better conditions working for their own business than they would likely get working for someone else's.
So do software developers in many other parts of the world. The difference is more that employment is a competitive market and the market rate for a decent software developer in the US tech hubs is recognised as being much higher than most other places so people moving jobs expect higher rates. Sadly, those rates do not necessarily need to be tied to productivity in any meaningful way, and so in much of the world software developers continue to be paid far less than the value they can generate because they don't negotiate well or bargain collectively to push salaries up.
However, it's not really a fair comparison. For example, in the UK, a lot of us solve that problem by going independent at some stage. At that point, you are dealing with clients on a business-to-business basis where fees charged can be related to value generated, and if you know what you're doing and get results, you can far exceed the income that almost any salaried software development position will offer.
Similarly, there are a lot of small tech firms here that are not SV-style startups with big funding and aiming to be the next unicorn or to fail within a relatively short period. They're just a few people who've got together to take on bigger projects or invest in more infrastructure or otherwise scale up, and they're happy to be doing that indefinitely and again making better money and enjoying better conditions working for their own business than they would likely get working for someone else's.