Because the conversation is incomplete if we're talking internationally.
The cost of living in the US is much higher compared to most other first world/rich countries for one. Count up someone's basic living expenses in the US and those in another country (so taxes, rent and fixed costs) and the US often ends up much higher in terms of absolute values. In other countries, taxes usually soak up more of those fixed costs, reducing them more across the board for most people. The US also has very little protection against surprise fees at checkout (to the annoyance of non-Americans when ordering stuff online from the US), so a lot of stores sell on higher markups relatively speaking, making the same goods more expensive in the US. There's also healthcare, which needs little elaboration because the US is to my knowledge the single most expensive country to live in when it comes to that.
That applies to the US as a whole; it's why someone can say they're making 300k USD a year, say they're apparently barely able to stay afloat and then the rest of the world pretty much regards the US economy as being fundamentally wrong in some form. In most places, 300k USD a year is living in the upper class (as in, "work this job for a decade and you can retire early" money), not scraping the bottom of the barrel. By modern conversion standards, that's about 263k euros, or about 21k euros each month.
Then there's the tech sector specific problems. San Francisco is expensive to live in, and most US tech companies are in SF. Take the US cost of living problem, amplify it specifically for the tech sector (which is usually not talked about, since it's hard to vocalize). Second is that the US tech sector has more creative ideas and money than business sense - throwing money at a problem like the purse doesn't exist is a very US tech thing that doesn't apply anywhere else. It means that it's possible to hire people at far more inflated prices than the job is realistically worth.
Whether a wage is good or bad is pretty much entirely dependent on the local economy. Someone making 2000 EUR a month in Europe makes just above/right below the poverty line. Someone making 2000 EUR a month in Brazil is living an upper class lifestyle. That's an extreme comparison, but is a good indicator.