It's possible that people in the industry want better working conditions or more equal/open pay systems, not just more money. Better hiring practices could be nice too.
In the US, software developers are highly compensated by local standards almost regardless of where they live. That was not always the case decades ago but it is today.
If you look at the top 10 states for software jobs, you will see that they fall in the higher end of the distribution for cost of living.
Even looking at your cheery picked example, we see the salary and cost of living track roughly - median dev salary is about $95k based on multiple sources and COL is about 7% lower than the national average.
Yes, devs do tend to fall on the higher side of a local median than others. Hence my point about unions not being just for more money.
110K sounds great, now divide by 80 hour weeks. Now it is nominally 50K.